COMPARISON OF FULFILLMENT OF PUBLIC INTEREST IN AN URBAN SPACE WITH THE EXAMPLES OF KOLIZEJ IN LJUBLJANA AND CINEPLEXX PALACE COMPLEX IN VIENNA

The practice shows growing investment pressure on important city locations. We wanted to know how effective was the fulfilment of public interest potential in two of such cases. For this study, we selected a case study method to compare two important projects: one in Ljubljana (the area of the former Kolizej – now Schellenburg), and one in Vienna (the area of the former Cineplexx Palace – now Danube Flats). The results of the survey show that the maturity and predictability of the planning system can have an impact on the greater fulfilment of the public interest in an urban space. Both characteristics allow projects to develop more consistently. In this respect, it is essential that the negotiating parties (the city administration and the investor) have flexible urban planning instruments, which are essentially aimed at securing spatial public interest. This enables a better response to the particularity of individual cases and to achieve a better outcome, that is at the same time in both the private and public interest. KEY-WORDS public interest, urbanism, space, negotiations, city, investor Aleksander Vujović: PRIMERJAVA URESNIČITVE JAVNEGA INTERESA V PROSTORU NA PRIMERIH OBMOČIJ KOLIZEJA V LJUBLJANI IN KINO KOMPLEKSA CINEPLEXX PALACE NA DUNAJU Aleksander Vujović: PRIMERJAVA URESNIČITVE JAVNEGA INTERESA V PROSTORU NA PRIMERIH OBMOČIJ KOLIZEJA V LJUBLJANI IN ... Aleksander Vujović: COMPARISON OF FULFILLMENT OF PUBLIC INTEREST IN AN URBAN SPACE WITH THE EXAMPLES OF KOLIZEJ IN LJUBLJANA ... 30 DOI: https://doi.org/10.15292/IU-CG.2021.09.034-047 UDK: 711.432:332.2 SUBMITTED: September 2021 / REVISED: October 2021 / PUBLISHED: December 2021 1.02 Pregledni znanstveni članek / Review Scientific Article


INTRODUCTION
In 1938, the famous sociologist Louis Wirth gave some important definitions of a city. While defining a city, he also concluded that city dwellers are organised into a number of social groups based on their common interest. This organizing is based on a collective effort to use advantages and resources for the dweller's own benefits. At the same time, the great diversity allows for dwellers to belong to several different social groups, which means increased social mobility, anonymity and freedom of choice (Wirth, 1938). History therefore teaches us how the city, as an area of all-round densification, brings substantial benefits for both the individual and the community, but also poses a difficult challenge of reconciliation between different interests, which is reflected in the city space. As space in a city is a very limited and precious commodity, especially in dense urban formations, it is subjected to different visions and ambitions, which all stem from different interests. In modern societies, citizens elect municipal authorities, which organise various professional bodies to assess and reconcile different private interests, but above all they have to secure public interest in urban space on the grounds that are important to all city dwellers. We are here referring to the conflicting interests of different stakeholders, who gain or lose from certain city developments, if they did not align their mutual benefits beforehand. When planning major interventions in urban pace, what the public often sees is only the role and capital of the investor. But the investor is not the only stakeholder in this process. There is the aforementioned elected (municipal) authority. Then there is the building and architectural profession, that through professional bodies and organisations, suggest to the municipality most appropriate solutions. Last but not least, there is both the professional and the general public, which both have a constitutional right to participation and information. In addition to public hearings and submission of comments, the general public has other powerful instruments for voicing its opinion, such as a referendum on urban developments. As an important extension of the general public, the media can make an important contribution to informing, raising awareness or even promoting certain proposals. The coordinated consideration and participation of all stakeholders have the capacity to make significant contributions to solutions that maximise public interest in urban city space.

Public interest in urban space
Public interest is a concept that appears in many legal instruments of various different fields. It is defined as interest "that of the wider community and not just of the individual, and is identified and given substance in each specific case. Thus, the public interest, despite any additional conditions that may need to be taken into account when interpreting it, undoubtedly also has a value component, or, to be more practical, a political component" (Petek, 2019).
These modest definitions are not sufficient in practice, however, which is why city administrations in their work also pursue broader objectives that they define as being in the public interest, for instance through urban development in the city, through its economical "metabolism" and physical development.
If we want to analyze the notion of public interest, we must start with the notion of the common good, as known in philosophy since Plato. In his work The Republic he defines the best political order as the one that has "promoted social peace in an environment of cooperation and friendship among different social groups, each benefiting from and adding to the common good. "(Plato in Simm, 2011, p. 555). Marijana Vugrin, on the other hand, sums up that the right to property, "which we can no longer look at as an absolute and unlimited right to use and exploit a thing, cannot be pursued without reservation only in the private interest (Virant, 1996in Vugrin, 2005. In doing so, we must note that many real estate and consequently legal conflicts in Slovenia stem from the interpretation of the "inviolability" of private property (i. e. land, buildings, areas), which is still partially subordinate to the community interestpublic interest.
Zakon o graditvi objektov (ZGO-1), The Construction Act, had recognized for our analysis a too narrow term of the "built common good", which had been divided by the Construction Act into the ones of national and local importance. The latter is defined as a "built common good, which belongs to a network of the public infrastructure of local importance and public surface on them, as well as buildings or parts of buildings whose use is intended for all under the same conditions, such as road, street, square, passage and other public transport surface of local importance, market, playground, parking lot, cemetery, park, green area, sports or recreational area and the like "(ZGO-1, Article 2). However, this concept does not fully address the public interest, especially not in areas that are outside the lands mentioned before and the facilities built on them, but are at the same time publicly accessible. Therefore it does not address the public interest on private land.
The public interest in space is therefore realized on several levels (strategic documents and laws at the state and municipal level, OPN, OPPN, DGD, etc.). At each level, there is a set of instruments that directly or indirectly address the public interest.

2. Theoretical and practical basis
The review of the literature has led us to the conclusion that there are different development and legislative "families" when it comes to urban planning, which results in different practices between countries. Some of them are project-oriented (e.g. the English and American systems), based on well-established examples from the past, while plan-normative-oriented systems (e.g. the German and Austrian systems) are closer to the planning system in Slovenia.
For the purposes of this article we have chosen to focus on practice established in the city of Vienna. Among the relevant contributions, we would like to highlight Tarek Diebäcker's article Städtebauliche Verträge und öffentliche Räume (Urban development contracts and public spaces). This examines the effects of a specific instrument -the urban planning contracton public space, using a comparative method for two projects in Vienna. In 2014, the City of Vienna made it possible to conclude special contracts between the City and landowners, which are known as urban planning contracts. The author notes that these treaties are heavily used in the field of public space. Based on two cases in the city of Vienna, it investigates on which levels of public interest in urban space between the city and a private party have been discussed and agreed upon. The author divides each project into several spatial segments and assesses each one according to six categories. Among other things, he also examines different degrees of the resulting publicly accessible space. Diebäcker's analysis of the cases of the Danube Flats residential tower block and the Continental Hotel on the Heumarkt shows that preservation of the public character and interest can in fact be ensured by such a contract. The article also notes the growing tendency towards privatisation of public space.
In this article we will therefore be interested in the method used to fulfill the public interest in urban space and to what extent was it executed the public interest in urban space has been fulfilled through the (non-)use of urban planning instruments on two important locations in two cities: in Ljubljana and in Vienna. Because we observed extensive procedural and substantive development differences between comparable projects in Ljubljana and Vienna but with both on a comparable legislative basis, we decided to carry out a comparative analysis of the two cases and the urban planning instruments used.

Explanation of the method
For the purpose of studying the topic, we have chosen the case study method. In this case, the comparisons of events, situations are not quantitative, but qualitative. We cannot influence the course of events, but compare how different courses of events have triggered different outcomes (Yin, 2003). In this way, we observe events not (only) with quantitative levers through which we would describe the events but also through the usage of qualitative descriptions, which help us detect mechanisms that have influenced the development of projects, but cannot be scientifically quantified. Because we are looking at two long--term projects, which are complex and take place over several years, this method is the most appropriate.
As Robert K. Yin explains in his book "Case Study Research: Design and Methods", the essential questions in the case study method are: how something happened and why, which is similar to the historical method, but with an important difference for us: "The strength of the comparative method lies in its ability to address the full spectrum of evidence -documents, artefacts, interviews, and observations" (Yin, 2003, p. 8). It is this diversity of observation, where, in addition to the research, we can also directly contact the individuals involved in the observed events, that allows us, in our case, to get a holistic picture of the development and unfolding of the processes.
We have therefore opted for the comparison method. We have established objective criteria, by which we mean categories, to compare the characteristics of the two projects. The criteria were determined in such a manner that the data obtained are comparable to each other and that the results obtained can contribute to a conclusion on the fulfilment of the spatial public interest of the area. The categories of the criteria are: ■ Location, ■ Project phasing (development of the project through phases), ■ Change in gross floor area, building coverage ratio (BCR), value of floor space index (FSI) in both areas (before and after intervention), ■ Investment and duration of the project development (from intention to construction), ■ Urban planning instruments used.
When processing the data, we decided to define each criterion, which contains a description of both cases in the context of each category with an accompanying comparison or comment.

Selection of cases
We have compared the case of the redevelopment of the former Kolizej building of Kolizej in Ljubljana and the former cinema complex Cineplexx Palace in the Viennese district Kaisermühlen. The site selection criterion was a culturally comparable environment in Central Europe. Austria and Slovenia share a centuries-long history, which also includes similarly standardised spatial planning legislation. Schellenburg (on the Kolizej site) and Danube Flats (on the Cineplexx Palace site) are both distinctly urban projects. They are both extremely limited in space in comparison to the amount of space that is planned on their sites. They are, in a sense, on the edge of the city centre -Kolizej is on the edge of the district Centre, and in the context of a larger city, Danube Flats are only a stone's throw away from the city centre of the enclosed river island in the 22nd district of Kaisermühlen. In the context of each city, they are located next to a good transport infrastructure: Kolizej is at the intersection of important city thoroughfares (Celovška Street and Bleiwesova Street), while Danube Flats is at the intersection of a six-lane road (Donauuferautobahn and Wagramer Strasse). Both locations are directly adjacent to frequent lines of public transport and two stops away from an important urban node -in case of Kolizej, LPP (Ljubljana's Public Transport) stop Gosposvetska is nearby and two stops away is the LPP station Konzorcij, while Danube Flats is next to the U-Bahn station Reichsbruecke and only two stops away from Praterstern.

3. Data collection
We compared the data that was available and relevant for urban planning. Our research is based on two main corpora of sources: review of relevant literature (scientific and professional articles, media publications on the topic) and data collection through meetings and interviews (with institutions and investors).
In case of the area of former Kolizej, we have obtained the pictorial material and the expected gross floor area programme cut of the winning solution of the 2004 competition from the professional journal Wettbewerbe aktuell, published in 2005. For further evaluations of gross floor plans, we have relied on the conceptual designs of the competition's winning solution, which were published on Trajekt.org (Neutelings & Riedijk, 2004). As for other media coverage, we searched the websites of various media outlets for news and reports on the project. These sources helped us to obtain information on the history of Kolizej from its construction to its demolition, the timeline of all phases of the project from 2004 to 2021, and some specific estimates on the total gross floor plan, programme cut of gross floor plan and the height of the towers. There are, however, scarce mentions of the project on the website of Neutelings Riedeijk Architekts, architecture office behind the winning solution. Some more general information and images are archived on the Wayback machine website that archives web pages' content changes in timestamps, including the architects' webpage. For the material from the institutions, we obtained information from the Ljubljana Municipality decrees, published on their website (alongside with the information about the hearings of the proposals and amendments to the municipal detailed spatial plan for the area of Kolizej) and on the website of the Uradni list Republike Slovenije , Official Gazette of the Republic of Slovenia. At the time of the consultation on the proposal to amend municipal detailed spatial plan for the area of Kolizej in 2021, the latest decision of the Ministry of Culture was published (No. 3510-23/2020/4), which gives an insight into the current contractual agreement (on compensation for the unbuilt culture hall) and the one from 2009 (on compensation for the demolished monument under the condition of the construction of a large concert hall) (MOL, 2021). The INDOK archive at Municipality of Ljubljana's (MOL) Department of Urban Planning (DUP) holds some documentation of conceptual projects from the 1980s and 1990s and from the 2004-2013 period. The latter consists of the promotional material after the competition, conceptual designs from 2007, 2009 and 2010 done by Neutelings Riedijk Architekts, the expert basis for the OLN (a more detailed urban plan) for the part of the CO 2/16 development area of Kolizej (Krog, d. o. o., 2005), the conceptual design from 2013 (Hilmer Sattler Architekten) and the proposal for the municipal detailed spatial plan documentation from 2013 by the LUZ company (2014). The INDOK archive documentation provided most of the information on the project's layout in the individual phases and on the urban design parameters (gross floor plan, project programme, dimensions, etc.). On 7 September 2021, we asked the Ministry of Culture for a permission to inspect the agreement document from 2009. On 16 September 2021, the Ministry of Culture replied to us by forwarding us a document No. 3510-33/2008/25, the so-called "cultural heritage consent for the survey and removal of the heritage building" from 2009. Information about the latest current state of the project was found on the commercial website of the project Schellenburg, which conduct the sale of the apartments in new building. Through a phone call and an e-mail to Reitenburg Ltd., we obtained information on the gross and net floor area and the area dedicated to different uses (residential, commercial, etc.).
In the case of Vienna, the already mentioned article Städtebauliche Verträge und öffentliche Räume (written by Tarek Diebäcker) describes in detail the effect of the introduction of the urban planning instrument Staedtebauvertrag, urban planning contract, in the city-state of Vienna. The article focuses on the impact of the contract and the maintenance of the "public" on a private land, which is set by the contract. The urban planning contract for this specific project is not publicly available, but some researchers and journalists can obtain access to it. This article describes the main public benefit measures of the project Danube Flats. The article on the website of the trade journal Architektur aktuell describes the historical arc of the process and provides some gross floor plan data. Media publications have given us an insight into the history of the process and the necessary gross floor data, but with slight contradiction between the data available in online articles by ORF and Der Standard by Martin Putschögl, the commercial website for the sale of the apartments in Danube Flats and the websites of the investors SORAVIA GmBH and S+B GmBH. The website A01 Architects provides the most comprehensive overview of the gross floor areas and dimensions of the project. These figures were taken as a basis for the assessment of other parameters (e.g. the aforementioned FSI and BCR). As far as the data about spatial plan and land use in the City of Vienna is concerned, we have obtained Plandokument 8079 from the official city website, which features an explanation in text and graphic of the changes that have been implemented so far in the spatial plan for the small area of the district of Kaisermühlen: namely permitted uses of space, height dimensions, general traffic layout, layout of public areas, etc. The local Chamber of Architects (Kammer der Architekten und Ingenieurkonsulten) was the source of certain gross floor plan data. We contacted the commercial office of the Danube Flats and the office of A01 Architects via phone and e-mail for general information on the gross floor areas and the programme mix of the Danube Flats project. They refused to answer our questions by phone -the impression is that this is due to confidentiality business etiquette. We have never received an e-mail reply either.

The locations are comparable
As cities, Ljubljana and Vienna belong to different classes when it comes to the size. But regardless of this difference, two areas under consideration have quite a few similarities. Both sites are located on the edge of an important and demarcated space: Kolizej is situated on the edge of the wider city centre within the inner ring of the city. The area of the Ljubljana around Kolizej, at the intersection of Gosposvetska Street and Župančičeva Street, has long been an urbanistic neuralgic point in the space of the wider city centre, while the Cineplexx Palace is located on the edge (along the waterfront) of Viennese district Kaisermühlen, which is surrounded by the new canal of the Danube (Neue Donau) and the old branch of the Danube (Alte Donau). The area is dominated by residential housing, recreational areas and the rapidly developing Donau City, an administrative and business centre with high-rise buildings. Any treatment of the area is controversial, or at least delicate, precisely because of the micro-location of the intervention. The project envisages a tall and varied building structure with a hybrid programmatic design that could easily fit into Donau City. Yet the site is located beyond the six-lane Reichsbrücke, on a side that is heavily dominated by residential development.

2. How both enterprises unfolded
Although the cases are similar in many ways, the outcome of the projects was quite different. It is precisely these differences that are the subject of our interest.

The Kolizej to Schellenburg case (Ljubljana)
Businessman Josef Benedikt Withalm built a multi-purpose military accommodation building in Vienna and Graz, and in the years 1845-47 also in Ljubljana. The barracks were built on the outer edge of the town in a gravel pit (Kolizej, d. o. o., 2004). The building had 126 rooms for accommodation, pub, café, bakery and indoor riding arena. In 1851, an evangelical church was built next to the barracks (Dolničar, 2016) and eventually, the town eventually grew around the complex. The building was later used for housing and craftsmen.

1 st phase: Potential for preserving heritage from demolition (1847-2011)
After World War II, the building was nationalized. Before its demolition, it had been in a very bad state for a long period of time, and was used only as emergency housing for more socially deprived residents. In 1993, the building of Kolizej was de-nationalized and declared a monument of local importance (Krajčinović, 2011). Then in 2003, the building was bought by the investor (DK, 2005). The old building of Kolizej was thus the last building of its kind in Slovenia from the time of the Austro--Hungarian monarchy, its purpose constantly adapting to the needs of a particular period.
The scenario of preserving the old building had the potential of renovation and/or adaptation with the same or new activity. This would preserve a relatively rare monument building and make it useful for a variety of modern programs. There could also be an intermediate solution, where the monument retains only the outside look, and inside a new spatial concept is implemented. However, this option was not realized either. Examples of creative and quality modernization and renovation of architectural heritage from abroad (such as the renovation of the central market Mercado de Santa Caterina in Barcelona by the famous architect Enrico Miralles) show us, that we could make use of instruments, that would in close cooperation with the relevant institutions (The Institute for the Protection of Cultural Heritage of Slovenia (ZVDKS), administrative units, Chamber for Architecture and Spatial Planning of Slovenia (ZAPS), etc.), enable a good architectural intervention and the modernization of the old Kolizej. In this way, essential spatial qualities could be preserved by monitoring the functional needs of modern times, and at the same time the project could be commercially interesting, so it would actually be profitabile. Moreover, by negotiating within the instrument of an urban planning contract as known to ZUREP-1 or as it is known in Vienna (Städtebauliche Vertrag), the modernization of both the complex and its surroundings in the public interest could even be achieved. By this we mean the possible arrangement and opening of the city parterre on the ground floor, content hybridization with important programs for the city and increasing the accessibility of the previously fenced surroundings. The investor could perhaps be allowed to build up a denser and slightly higher part of the area outside the monument building parallel to the villa on Župančičeva Street.
In addition, the investor could additionally invest in public space outside the investment area, such as the modernization of the Slovene Reformation Park, or in the sustainable mobility sector: multi-purpose (interchange) rearrangement of the nearby bilateral bus station Gosposvetska or slightly more distant Tivoli railway station.
By preserving the building, the more or less accordant memory of the activities that once took place in the complex could be preserved in various ways. On an urban scale, the density of construction for this area would remain reasonably high, and the city would retain one of the most coherent parts of the building fabric in this area.

2 nd phase: Novi Kolizej -The public interest in the 2004 architectural competition winning entry
However, a series of decisions has led to the intention to demolish the building and build a new one. This was partly a result of the opinion that a part of the construction profession had at a time. They believed that it was extremely difficult to rebuild the same building and meet the earthquake-resistant standards (according to MMC RTV SLO, 2008). The decision was also influenced by investor's expectation of large new areas (approx. 90,000 m 2 gross).
Since the decision to demolish the building has already been taken, the best way to deal with the development of the planned area is to have a clear urban planning base and then to launch competition as wide as possible. In 2004, an international competition, which was invite-only, was indeed launched, in which six renowned international architectural firms participated. However, due to the lack of consideration of boundary conditions and context for such an important area, and with that too loose initial constraints of the competition, most of the solutions obtained have rightly provoked disapproval from the professional and general public alike. This is the point at which the absence of proper use of the instruments essential for this step has made a key difference in reduction of the potential for realizing the public interest.
The winning solution by the Dutch firm Neutelings Riedijk stood out from its surroundings because the tallest part of the complex -the north-east tower -measured 96 m, which is much higher than the general anonymous fabric of the surroundings. Most notably it was higher than any of the nearby landmarks: the bell tower of the neighboring Evangelical Church, the tower of Hotel Lev, and the skyscraper Nebotičnik. However, the proposal represented a rather diverse programming hybrid with a concert and performance hall for opera and classical music, which was called "new cultural heart of Ljubljana" (Kolizej d. o. o., 2004), retail space, commercial space, two multi-family villas for 32 flats and five underground floors (four garage floors) with underground access from Župančičeva Street and a connection for a later underground connection to the swimming pool Ilirija under Tivolska Street (Kolizej, d. o. o., 2004) (Kolizej, d. o. o., 2004. The total gross floor area of the competition proposal was expected to be 98,000 m2 ("Novi Kolizej morda do leta 2012", 2007), which represents approximately 6.5 times the capacity of the old building. At the time, the investment was estimated at 120-150 million euros (Kladnik, 2004). The current smaller and different project being built in 2021 has been estimated at 90 million euros (Citylife, 2020). This solution, selected through a competition, posed a strong challenge to the established spatial order, but at the same time it represented a proposal for a city-forming hybrid with diverse program that would be in service of the city, by providing additional capacities for the activities needed in the city.
Simultaneously the design and scale of the proposal offered a relatively luxurious publicly accessible ground floor space on the site. In particular, we are referring to the plaza at the junction of the proposed complex and the existing former Workers' Home building.
The public interest potential of such a proposal can therefore be assessed as medium. The solution from 2009 was characterized by a total gross floor area of approximately 96,000 m 2 (Neutelings Riedijk Architecten, 2009). The towers were lowered and levelled to 73.8 m, which is very close to the established maximum height of nearby exposed landmarks in the wider city centre. The central cube, the plinth, presented a concert and event complex with a "grand opera hotel". On the plinth, twin towers were envisaged with hotel suites and a glazed observation terrace (glass roof at 53 m). Space for the event setup with the auditorium was increased from 14,000 m 2 to 26,000 m 2 , allowing different configurations depending on the type of concert (between 1,112 and 1,332 seats). The hotel service covered 20,500 m 2 . The office and retail space was reduced to a total of 6,000 m 2 . The previous setback of the complex from Gosposvetska Street, which created a small public plaza, is now fully occupied by the business and retail wing. The number of dwellings are both reduced: number of apartments has fallen from 32 to 11, or in terms of size from 8500 m 2 to 4500 m 2 . Instead of two, there is a single correctly placed tower/vilablock (5 overground floors) with a common underground part of the "Opera Hotel".
Through the admittedly undefined instrument of direct negotiation which nonetheless ensured a better fit into the broader spatial context, the contemporary design and form of the envisaged building were preserved. More importantly, the diversity of the building's program has been preserved, including the enlarged music hall. We therefore consider that such a proposal has a relatively high public interest.
Nevertheless, it was still a complex that stood out from the general urban fabric in terms of volume and height. Despite the compromise, it remained so because of a series of earlier mistakes, which arose from the inappropriate use of existing instruments described above. But regardless of this, compensation instruments familiar from other contexts, such as the purchase or replacement of air rights (e.g. New York or Boston), could come in handy at this stage. Under this instrument, if there is already a permissible extreme increase in gross floor area or a deviation in terms of volume or height, this excess is charged or "neutralized" with an investment in the development of (not necessarily adjacent) public space or, for example, into a program of building non-profit housing. Such instruments also allow, and even encourage, compensation to take place in the treatment area itself, either in terms of additional publicly accessible space or in terms of a share of the space reserved for legal persons acting in the public interest. On 10 August 2011, the demolition of the old building of Kolizej began (Siol, 2011).

4 th phase: Project Schellenburg (2013-present)
In October 2012, a special commission of the Ministry of Education, Science, Culture and Sports decided that the project of the New Kolizej must respect the height restrictions that were in force in the spatial plans at that time, i.e. at 30 m. According to the opinion of the majority in the commission, a conservation plan should be a prerequisite for the preparation of the Municipal detailed spatial plan with the new permitted dimensions, as the project is located in the area of the Decree on the designation of monuments of natural and cultural heritage in the Ljubljana Centre area between Aškerčeva, Tivolska and Slovenska street (Jesenšek, 2012).
The Ministry justified the establishing of a special commission saying that: "The conservation plan for renovation is a relatively new instrument of urban planning in heritage areas, with which we do not yet have enough practical experience. " They also remarked that: "the case of the Kolizej is certainly one of the most difficult and complex spatial challenges" (Jesenšek, 2012).
This was followed by a partial change of investor. City Council of Municipality of Ljubljana adopts a different Municipal detailed spatial plan on 20 January 2014 (ODLOK o občinskem podrobnem prostorskem načrtu 106 -Kolizej, 2014), allowing a different type of development. Instead of a large, articulated volume and a tower, this time we are dealing with a lower, H-shaped courtyard city-block building with additional thickening of the lamella along Gosposvetska Street, and an inside atrium. On the south--western edge, the tower remains, but it is aligned with the villa along Župančičeva Street. Compared to the competition proposal of Phase 2, the new proposal offers much less public space at ground floor level, but more than in Phase 3 of 2009.
On 18 February 2020, the investor informed the Ministry of Culture that they will not be able to ensure the implementation of the compensatory measure -a central multi-purpose space (a concert hall) in the new facility. The Ministry of Culture therefore imposed an alternative compensatory measure on the investor of the new building, namely the payment of a sum of money equal to the value of the damage caused. The damage was imposed on the basis of the estimated value of the construction works and the associated costs for the fitting of multi--purpose hall and the ancillary spaces of 600 m 2 (Ministrstvo za kulturo, 2020, p. 2). The public hearing of the initiative for the amendment of the Municipal detailed spatial plan for area 106 (Kolizej) was held between 17 August and 1 September 2021 (MOL, 2021).
In our opinion, by using this instrument, the Ministry has decreased the realization of the public interest, since the real benefit in urban space (the multi-purpose hall) has been exchanged for a lump-sum penalty.
While the proposal for Phase 4 includes an appropriate densification of the urban block in the city centre, the project is dominated by luxury apartments with a small commercial and retail component. This has resulted the public interest being realized foremost in supporting the existing spatial order and the aforementioned densification of the area in question, which is located in the wider city centre, but with a much denser built-up area than at the time of the old building Kolizej: the difference in value of FSI before and after the intervention is almost three times. Nonetheless, filling the building gap left by the demolition of the old building is a positive development. The proposal is significantly depleted in terms of the program, as the measure eliminates one last amenity of interest to the general publicthe multi-purpose hall, which has already been reduced in size compared to the first proposal.
From a spatial planning viewpoint the last phase of the redevelopment of the Kolizej area in comparison to other phases seems to have the least potential for public interest realization. At the same time, this is the version that will actually be materialized. Until 2019, the site was home to a cinema complex with an indoor children's entertainment area Minopolis. In autumn 1999, a cinema complex was built according to the plans of architect Harry Seidler (Putschögl, 2019b). Prior to the subsequent amendment of the spatial plan, the zoning of the site was described as "mixed residential with commercial activity with category V" (max. height up to 26 metres). The zoning documents prohibited the construction of housing on the site (Putschögl, 2015).

The Danube Flats case in
Before the demolition, the complex was comprised of approx. 12,000 m 2 net of above-ground usable floor area (Kammer der Architekten und Ingenieurkonsulenten, 2014), 28,000 m 2 of gross floor area, and 160,000 m 3 of volume (Ostertag Architekten). Architecturally, the complex was average, but the potential for preserving the cinema complex was in the cluster of activities made possible by the multi-purpose halls and the associated facilities, which were primarily intended for the local community in the district of Kaisermühlen.

2 nd phase: Public interest in the winning competition entry in 2012
The competition was launched on 19 April 2012. The competition area covered approximately 1,24 ha. The competition brief called for the layout of the residential area, paying special attention to the design of the ground floor -the base of the building. Competition was organized by investors themselves in accordance with the rules of the City of Vienna. On 5 September 2012, it was announced that the winning solution is the design by Project A01 architects ZT Gmbh. (Danube Flats, 2013).
The official Danube Flats website (2013) describes the winning project as "a tower block about 150 m high with 500 flats on 47 floors and three smaller apartment buildings" with a "a partial overlap of the motorway approach". The complex would include a "supermarket, a convenience store, a bakery, a medical centre, a café and a restaurant in the base of the tower" and a "Skybar in the upper third of the tower". The complex is characterized by "attractively designed public spaces integrated into the existing environment", "public pedestrian access to the New Danube", "garage parking spaces for electric cars", "amenities for car--sharing", "luxury bike storage for residents" and "proximity to a metro station". The tower base and the tower itself are intended to act as a noise barrier between Wagramer Strasse on the Emperor's Bridge and the quiet residential and pedestrian area (Danube Flats 2013).
The public interest issue lies mainly in the design of the housing program where it is not allowed, and in the huge expansion of the allowed built-up area. The amendment to the zoning plan would allow more than 45,000 m 2 of net floor area in two residential buildings (Kammer der Architekten und Ingenieurkonsulenten, 2014).
Based on the planning documents, more than 500 apartments would be built in this attractive location directly on the New Danube, with a new building typology VI (Bauklasse VI). Approximately 300 of them are in a 150-metre-high tower, the rest in a lower building (Putschögl, 2015).
Despite its serious shortcomings (high building efficiency, risk of gentrification of the area ), the competition project promised a relatively varied set of functions, at least in the base of the building. Therefore, the achievement of the public interest at this stage can be assessed as medium.

3 rd phase: Urban planning contract and zoning plan amendment (2015)
The urban planning contract was signed in 2015 (Putschögl, 2015). On 1 July 2015, the City Council adopted amendments to the spatial plan for the area (Plandokument 8079, 2015). In the contract, the investor commits to bridge the two road entrance ramps (Diebäcker, 2019 andPutschögl, 2015) with a unified pedestrian surface connecting the waterfront and the existing residential neighborhood, to transform the New Danube waterfront and the station forecourt of U-Bahn, to provide a windproof design for the building, to create a kindergarten in the base of the tower, to expand the nearby primary school and to offer 40 apartments for the socially disadvantaged. These contractual measures are worth €10 million (Putschögl, 2015). More in chapter 3.5 (Urban planning instruments used).
The competition phase envisaged a high-rise building next to three low-rise buildings. Since 2015, the spatial plan on this site (graphic and text part of Plandokument 8079) allows only two mixed-use buildings. In this phase, the number of lower buildings is reduced to one single building and limited in height to 26 m. The second may be a "special building", a high-rise, also with commercial activity. The complex must have a minimum of 2000 m² of total usable area above ground for cultural, artistic, social and educational use. The total residential floor area may not exceed 36,000 m² of usable floor area. The building must be a landmark. The tower may have a maximum height of 167 m above the "Viennese ground zero" (standard reference point of 156.68 m above sea level. Appartments can only be built from 9,5 m above the ground. On ground floor, commercial space is expected. The allows for a maximum volume of the above-ground part of the building of approximately 196,000 m 3 (167,000 m 3 + 22,000 m 3 + 7,000 m 3 ) (Plandokument 8079, 2015).
As a key urban planning instrument, the Urban planning contract has brought substantial improvements in favor of the public interest in space, and the potential for realizing the latter has increased substantially.

4 th phase: The final project and the state of construction today (2019-present)
On 18 December 2018, the court confirmed the validity of the building permit for the Danube Flats project (Architektur aktuell, 2019). The A01 Architects website announced 550 apartments, a kindergarten, a medical centre, shops, restaurants. On a narrow site of 11,500 m² and a wider site of 23,737 m², will be built 54,500 m² of net and 67,500 m² of gross floor area, 183,500 m³ of volume, a 150 m tall tower (A01 Architects, n.d.). The complex would eventually include: private apartments, "investment apartments", "subsidised smart apartments", gastronomy and shops (Soravia GmBH, 2019). The complex would contain around 42,000 m 2 of above-ground usable space and the tower would have 49 storeys (Architektur aktuell, 2019).
In the investor's press release, the accompanying building next to the high-rise is described as a 160-apartment residential building with surrounding terraces overlooking the New Danube. It will have approx. 10,000 m 2 of usable floor area on 9 overground floors. From the start, it was conceived as an investor project intended for rental housing. Most of the apartments will be spacious 1-to 2-bedroom apartments with terraces and full-wall glazing. All residential floors will have small rental office units, "home offices". The commercial ground floor will have basic amenities for the residents and a medical centre (Soravia GmBH, 2021).
Unlike in the case of Ljubljana, the relationship between the city administration and the investor, as well as the project itself, did not change significantly through the implementation project, as the agreement between the investor and the city was not changed during the process in any way. It has only become more concrete through the phases, especially in the context of the materialisation of the public interest in space. Therefore, the realisation of the public interest in space can thus be considered relatively high in this phase.

Changes in gross floor plan, BCR, value of FSI (before and after the development)
As the Table 4 in Appendix reveals, for both projects the gross floor plan and consequently the value of FSI increased significantly after the development intervention, although it was already decently high for the environments, in which the buildings were located before the demolition (LJ: 1.6; VIE: 1.15). The BCR has increased by only 3% in Ljubljana case, while in the Vienna case it even stayed the same. The difference in the projects is that the rest of the area in the case of Vienna is laid out as a varied urban plaza (mostly with roof over the garage area, the import and the motorway), dotted with green islands, with everything being publicly accessible. In the case of Ljubljana, however, most of the remaining part of the area is private and intended for future occupants (with possibility of complete fencing). What remains in the public use are the pavements, which have been rather lavishly extended into the arcades below the building at the junction with the public amenities, the road and the associated pavements with the driveway for the largest building and the tower at the southern end of the project. From this point of view, it can also be concluded that the two projects are different and that the Viennese one has the potential to fulfil more of the public interest in urban space.
The Tables 3 and 4 (in Appendix) also clearly show that the Ljubljana project varies in most parameters according to phases. The Vienna project is more stable, with the fulfilment of public interest in urban space constantly increasing. Fluctuations mean uncertainty for both the city and the investor. Although in the specific case of Ljubljana, the investor made a relatively large profit, the uncertainty could also have deterred the investor from the project. Nor is this the best incentive for potential reputable investors in the future who wish to invest in our environment. Stability and consistency of procedures are therefore in the interests of both sides.

4. Investment and the duration of the project development (from intention to construction)
Both projects have a private, corporate investor. In the case of the former Kolizej, now Schellenburg (Ljubljana) project, the redevelopment of the area started to be planned as early as the 1990s: e.g. with the programme studies of the company IZTR in 1991 and 1993. Since 2003, the most serious investor so far has invested €12 million into the purchase of the building, the land and the competition by the end of 2004 (STA, 2004), and a total of €30 million by 2012 (Petkovšek, 2012). These figures and other actions show a serious intention to invest and develop the area. The value of the project is estimated at 120-150 million euros in the second phase (Kladnik, 2004), in the third phase (adapted competition solution) the value of the project grew to 130 million euros (60 million euros would cost a non-profit concert-opera hall) (Petkovšek, 2012), while the total value of the project in the final phase is estimated at around 90 million euros (Citylife, 2020).
In the case of the Danube Flats project in Vienna, Der Standard mentions the current developer as the owner of the cinema complex since 2005 (Putschögl, 2019b). Soravia GmBH and S+B GmBH are mentioned in 2012 as the main initiators of the Danube Flats project (Putschögl, 2012). In the second phase before the signing of the planning contract, the cost of the project is estimated at €140 million (Putschögl, 2019a). At the time of signing the planning contract, the City of Vienna proposed additional measures, valued at €10 million. In the final phase, the cost of the project is estimated at €253 million, or according to some sources €250 million respectively (ORF, 2018/ Putschögl, 2019b. The development of the project in the Ljubljana case has thus lasted 17 years (2004)(2005)(2006)(2007)(2008)(2009)(2010)(2011)(2012)(2013)(2014)(2015)(2016)(2017)(2018)(2019)(2020)(2021). The development of the Vienna project has so far lasted 9 years (2012-2021), despite significantly higher gross floor plan and higher investments in additional measures. Both areas are currently under construction. It is in the public interest to keep development and construction as short as possible, as both have an impact on the development and functioning of the whole surrounding area during both the development and construction. For the investor, predictability of duration also makes it easier to plan financially both for the project and for their own financial balance sheets.

5. Urban planning instruments used
As the Table 1 in Appendix shows, in the Ljubljana project, several urban planning instruments were used. The building of Kolizej has had the status of a local monument of immovable cultural heritage since 1993. In 2004, an international architectural competition was organised: participation was allowed via invite-only, and the competition was outside the domain of Slovene Chamber of Architecture and Spatial Planning. In 2005, the building of Kolizej was temporarily declared a monument of national importance for a period of one year. In 2009, an agreement was reached between the investor and the Ministry of Culture on compensation for the demolition of the monument: a construction of a cultural activity (a hall) on the site of the new building, the payment of the project documentation for the renovation of another monument (the building of Cukrarna), and the payment for the repair of the roof of the latter monument. A year after the demolition of the old building of Kolizej in 2012, a special commission at the Ministry of Culture decided that the urban planning instrument-conservation plan was a prerequisite for the preparation of a master plan within new permitted dimensions, as the project is located in a specific area of the ordinance that protects heritage in the Ljubljana Centre district.
After the demolition of the monument in 2011, an agreement for non-compliance with the agreement on the construction of a cultural hall as a compensation for the demolished monument was reached in 2020 (Ministrstvo za kulturo, 2020).
The table 2 in Appendix tells that in the Vienna case, the following urban planning instruments were used. In 2012, an architectural competition was organised. In 2015, the investor and the city signed an urban planning contract (Städtebauliche Vertrag), whereby the investors committed themselves to additional investments in public interest worth €10 million on and off the investor's land (Putschögl, 2015). In the contract, the investor commits to bridge the two road entrance ramps (Diebäcker, 2019 andPutschögl, 2015) with a unified pedestrian surface connecting the waterfront and the existing residential neighbourhood, to reconfigure the New Danube waterfront and the waterfront vestibule of the U-Bahn station, to provide a wind-calming design for the building, to build a kindergarten in the base of the tower block, to contribute €3.86 million to the expansion of the nearby primary school in the district of Kaisermühlen, and to offer housing for the socially disadvanta-ged (Putschögl, 2015). For the latter, the investor has to build 40 apartments (Smart Wohnungen) in terms of size of "1,200-1,400 m², each with approx. 30-40 m² of usable living space" with "the usual level of furnishment". (Putschögl, 2015). In creating a new unified pedestrian surface, the investor (Danube Flats) must purchase the overlapping surface of one of the road entrances and maintain it at all times but leave it fully accessible to all members of the public. The second pedestrian overpass has to be built by the investor too, but ownership and maintenance will be taken over by the City of Vienna, which will also keep public access in place. The purpose of the pedestrian overpasses is to reduce noise emissions to the surrounding residential buildings and to improve building contact with the waterfront (Diebäcker, 2019, chapter 4).
The Vienna case has thus achieved extensive public interest acquisitions both on and off the site, while the Ljubljana case has relatively modest public interest acquisitions in its final stage. In the Vienna case, the final effect was mainly a result of the instrument of the planning contract, which ensured that negotiations were conducted in a relatively transparent and efficient manner and that the agreement was legally binding for both parties.

DISCUSSION
From the insight into the genesis of the projects, it can be concluded that compared to some other examples from nearby abroad, specifically the two Viennese examples described in Tarek Diebäcker's article, the process in Slovenia, especially for key development projects, is slower, the development and implementation of the projects take longer, and the public interest in the area is realized only to a small extent. A positive side of such processes is the absence of hasty solutions which can be detrimental to certain places. There is a lesser chance for gentrification and touristification.
In the development of the Ljubljana project on the site of the former Kolizej, urban planning instruments that were used are: protection (the status of a local monument of immovable cultural heritage, temporary protection for a monument of national importance for one year), international competition, compensation for the demolished monument (provision of the hall, payment for the project documentation for the project Cukrarna, payment for the repair of the roof on the same project), compensation for the non-compliance with the agreement on the construction of the hall, the conservation plan and a passing and amending of the Municipal detailed spatial plan.
However, some other key attempts at measures based on different instruments to achieve the public interest have been missed, as we know from the Vienna case, for example: the investor could have made part of the apartments available for non-profit rental. This would contribute to social diversity and housing affordability and make the area less likely to undergo the process of gentrification. A similar measure would be the commitment to invest further in more housing capacity in another location. At the same time, the investor could invest in the renovation or improvement of the public space both on and off the site. It could invest in sustainable transport infrastructure for the city. There are no appropriate urban planning instruments available to achieve the latter. We also lack urban planning instruments that would allow better professional coordination between the different levels of decision-makers in the public interest (e.g. city authorities, The Institute for the Protection of Cultural Heritage of Slovenia, Ministry of Culture).
The data we have collected show that the sophistication of the planning system can have an impact on the realisation of the public interest in space. It also allows projects to be developed more consistently. The Vienna case, despite the complications with the implementation of the new instrument (the urban planning contract), shows a greater degree of stability, less uncertainty and a better result. Although both systems are based on normative planning principles (typical of the wider Central European area), today they show some significant differences. In some key segments of spatial planning, the Viennese example, unlike ours, allows for more flexibility, especially in negotiations between the city and the investor. Thus, we can conclude that a rigid normativeness to a minimum is often not in the public interest, as the cases in which the normative is applied can vary considerably from one another. In practice, it often turns out that the minimum required by the law can also become the maximum that the city can demand from the investor. What is more, it can even happen, as in the case of the concert hall within Kolizej, that despite the minimum size, the latter does not materialise at all. Comparison with other instruments in other countries reveals that it is not enough to develop only one urban planning instrument, but that in practice often a combination of several instruments is needed. This will allow us to better respond to the particularities of individual cases, which we mentioned earlier, and to achieve a better result in both the private and the public interest.
Through an analysis of the publicly accessible space in both new projects, we can confirm Diebäcker's observation that there is a growing tendency to privatise space as much as possible.
In the case of Ljubljana, the latter is more drastic, as typological diversity has been reducing with each successive phase of the project's development. Instead of the large plaza at the junction of the former Workers' Home and the new housing development along Gosposvetska cesta, which was envisaged in the competition solution, we will get just an arcaded oblong space with a pavement Whether internal courtyards are publicly accessible space we do not know.
In summary, the two key reasons for the minimal gain of public interest in an urban space in the too long course of development of the renovation project of the area of the former Kolizej building are an inconsistent or even inadequate use of existing urban planning instruments to ensure the public interest in space and a lack of greater flexibility within existing urban planning instruments for transparent, efficient, comprehensive and beneficial mutual negotiations between the investor and the public administration.

CONCLUSION
Unfortunately, in both cases, the finished products are hardly examples of highest quality architectural solutions. Yet, despite the similar starting points (demolition of existing buildings, construction of a multifunctional complex with a much higher utilisation rate, which is dominated by housing), the realisation of spatial public interest differs significantly.
The Ljubljana project, which is already under construction at the time of the survey, will end up as, in the terms of urbanism, appropriate development with mediocre architecture (although this has progressed in the proposals from neo-historicism to contemporary generic look). Once construction is complete, the painful gap in the city landscape will be gone, meaning the city life will go on. The problem of the realised solution that offers absolutely too little to the public (i.e. to all stakeholders) despite the outstanding location and the sacrificed monument (an inconspicuous footprint and some retail and commercial ser-vices on the ground floor) will quickly disappear, at least in the eyes of the general public. This is also why it is a good idea to examine and evaluate the process and the situation objectively. An analysis of the bad decisions, which were essentially caused by the absence of appropriate negotiating levers -instruments for securing fulfilment of public interest in urban space -can help to promote the usage of the existing instruments more decisively and courageously. Above all, such analysis encourages changes in the legislative field to introduce and implement new instruments that would help both the city and the investor to achieve better spatial outcomes in the public interest.
In addition to the mentioned existing instruments (which were often not optimally used), we would like to have additional instruments for better results in the realization of the public interest in the urban space in this field. Noticeable is also a varying degree of coordination of different levels: city, ministry, The Institute for the Protection of Cultural Heritage of Slovenia.
For further research, we think it would be relevant to study similar examples in Ljubljana: the area of Šumi, the Central Stadium in Bežigrad, the area of the central railway and bus station. Some have already materialised, others have not. But they all share complications, long development times and fluctuations in fulfilment of public interest over time. To eliminate the root causes some serious changes in the optimization of the work of often inefficient and uncoordinated stakeholders in the planning system should also be addressed. ■ offering housing for the socially disadvantaged; (Putschögl, 2015) additional data ■ bridging the entrance ramp to Copa Cagrana beach (Dibaecker, 2019)

LITERATURE AND SOURCES
■ building 40 apartments (Smart Wohnungen) in terms of size of "1,200-1,400 m², each with approx. 30-40 m² of usable living space" with "the usual level of furnishment" (Putschögl, 2015) PHASE 4: The final project and the state of construction today (2019-present) data no data source no data