Cultural Heritage: Vienna (Austria)

Vienna, an historic Central European metropolis, with approximately 1.6 million inhabitants, is a city whose development can be traced back over a period of 2,000 years. This historical development is still clearly visible in the urban texture, whose identity it defines.
The decision to revitalise the four vacant gasometers in Vienna-Simmering was taken in the mid-1990's; a development competition was organised in 1996 and won by the non-profit developers GPA, SEG and Gesiba. Jean Nouvel, Coop Himmelb(l)au, Manfred Wehdorn and Wilhelm Holzbauer were commissioned to plan the individual architectural projects. The refurbishment was completed in July 2001.

Context
This complex, the largest gas depot in Europe when built between 1896 and 1899, was shut down in 1986. It is situated in an urban industrial zone that for many years had been languishing. In the course of time, numerous adjacent large-scale enterprises were closed down too, e.g. the St. Marx abattoir.
At the same time, the location of the gasometers is extremely favourable: next to the intersection of the A23 urban motorway and the A4 motorway, which leads to Vienna-Schwechat Airport. Moreover, the Vienna Underground line U3 was extended to Simmering in autumn 2000, for which a separate station was built near the gasometers to link the gasometers with the city centre by only eight minutes' journey time. This area was thus ideally suited for targeted urban development.
From the beginning, it was the objective of this project, despite the extremely complex refurbishment required, to construct flats in these fine examples of protected industrial architecture that would meet high quality standards while being affordable for the average citizen. As this objective could only be met by the Viennese system of housing construction subsidies, the overall construction costs of ATS 2.5 billion (Euro 181.7 million) were subsidised by the municipal administration by ATS 310 million (Euro 22.5 million).
However, at the same time, the gasometer project is an important element of a new strategy adopted by the city of Vienna. When the lack of housing became too acute in the 1990's in Vienna, action had to be taken very quickly: the new construction volume was increased to approx. 10,000 subsidised flats per year - the projects were largely implemented in peripheral areas that were easily available. In the mid-1990's, the situation had steadied down sufficiently to permit a rethinking of this approach. The historic building stock, substantial parts of which have been preserved, is a key element of Vienna's urban appearance and of the identity derived there from. Earlier than many other European cities, Vienna took steps to protect its architectural heritage, and this architectural heritage remains an important economic factor for cultural tourism. Nevertheless the city of Vienna is very interested in providing sufficient space for the 'new', i.e. contemporary uses and architecture. In recent years, several large-scale historic objects have been rehabilitated and adapted for contemporary use and design. One of those revitalised objects are the gasometers. 
The refurbishment of the gasometers constituted a very demanding challenge for the architects: while the external appearance of these striking brick structures was to be preserved, their interiors were to house innovative flats and offices including extensive infrastructure to meet the state-of-the-art requirements of contemporary forms of housing and employment.
With this, the changes in the historic building volume were to be kept as small as possible. First, additional slits had to be cut in the external walls in addition to the existing - albeit nine metres high - windows to ensure that the interiors would have sufficient natural light. A total of 1,400 cubic metres of bricks were removed for this purpose. The historic metal dome structures, were also renovated but the covering was removed with the effect that the new inner courtyards became much brighter. However, before that the metal girders were tested in a wind tunnel, avoiding all edges or holes to preclude the development of disturbing whistling sounds in conditions of strong winds.

Programs
With respect to the interiors, the solutions implemented had to be modern and independent of the historic conditions. Each of the four architects (or teams) found different answers to this question.
The French architect Jean Nouvel systematically continued the 'light' theme inside Gasometer A and thus designed 'Austria's biggest sundial'. Sensitively combining historic and new materials, he lined the façade of the star-shaped housing structure with polished metal, which now reflects myriad light effects at different times of day.
The Austrian team Coop Himmelb(l)au perforated the surrounding façade of Gasometer B and thus created an external field of tension with a slightly projecting add-on that opens a wide vista on the nearby recreational zones of Prater and Danube (which can be reached directly via the "Pratersteig" footbridge). Inside, the circular motif of the existing structure is continued; a student hostel and, on the top storeys, additional flats are arranged around the circular inner courtyard. 
For Gasometer C, Manfred Wehdorn, the Austrian architect and monument protection expert, designed a 'house inside a house' and divided his inner structure into 18 segments of a circle. His answer to the circular shape imposed on the design is an inner courtyard shaped like a truncated cone tapering downwards.
Finally, Gasometer D was designed by the Austrian architect Wilhelm Holzbauer as a starshaped volume intersected by three internal spaces. His housing project breaks up the inner orientation of the old volume by having the loggias and terraces of the flats facing the open intermediate spaces.
However, the big challenge of the project not only lay in creating adequate housing space inside the brick structures but - and primarily - in providing a balanced mixed-use concept that will offer the new residents a full range of shops and services.
For this reason, the flats located in the former gasometers only start at a height of approx. 30 metres; the infrastructure facilities are situated below. These include the two-storey shopping mall that extends across all four gasometers. Approx. 20,200 square metres of retail space were created - in addition to shops and a supermarket, these premises will also house restaurants and a bank.
A combination of housing and workplaces, too, is provided for: the gasometers will offer a total of 11,000 square metres of office space. In addition, the Vienna Municipal and Provincial Archives formerly beset by space problems will find a new home in the gasometers.
An important complement to the combination of housing and work is provided by the 600-square-metre day-care nursery designed by Wilhelm Holzbauer. In addition to the excellent connection to the public transport system by means of the underground station, more than 1,000 parking spaces were created as well.
A wealth of entertainment options is furthermore available for the leisure activities of the residents: the bottom section of Gasometer B contains the 7,450-square-metre Bank Austria multifunctional hall which holds more than 4,000 people. This multifunctional event centre was designed as totally soundproof. As a result, the hall is a suitable venue, not only for conferences, fairs and exhibitions, but also for rock concerts, raves, clubbings or balls without creating even minimal noise disturbance for the residents above.
Moreover, the so-called 'skywalk' leads from the shopping mall level in Gasometer C directly to an entertainment centre designed by architect Rüdiger Lainer as a 'Pleasure-Dome': a façade of multicoloured glass envelops a multiple entertainment complex that includes e.g. 15 cinemas stacked one above the other as 'rocks' with lobbies and access zones stretching between them. Above, we find an entertainment mall featuring theme restaurants and shops on three levels. An additional sum of ATS 720 million (Euro 52.3 million) was invested in this entertainment centre.

Strategy
When the plans for the revitalisation of the gasometers were presented, some scepticism was encountered about whether the strategy adopted would actually work. However, both the population and the economic sector were definitely in favour of this approach: already one year before completion, all the retail space in the shopping mall had been leased. And when the tenants moved into their flats in early summer 2001, practically all the units had been sold or leased as well.
However, the revitalisation of the four gasometers is no isolated event in an otherwise unused environment, rather, the investment was intended to deliberately trigger the emergence of a new neighbourhood that is to take shape within the next ten years. And the success of this strategy, too, can be regarded as great. Intensive construction activities began in the immediate surroundings of the gasometers already during the refurbishment works. Before completion of the central project, not only the entertainment centre 'Pleasure-Dome', but also the office project 'Eagle + Ant' by architect Martin Kohlbauer had been completed. This combination alone made the location Europe's biggest construction site at the time - in all, the gasometers and their environment took up a total of 220,000 square metres of space, compared, for instance, to a total of 200,000 square metres in Berlin's Potsdamer Platz.
And there are vast additional areas whose land prices have already increased markedly while other sections are owned by the city of Vienna. In all, approx. 200 hectares are available in the so-called Erdberger Mais area - a development zone for a city quarter that is primarily aimed at satisfying the demands of the new economy. In the near future, roughly 10,000 new workplaces will be created here; the overall potential is estimated at approx. 50,000 jobs.
In the immediate vicinity of the gasometers, we find the St. Marx abattoir, closed down a few years ago, where the existing - partly historic - building volumes may be likewise used for another 'anchor project', a development favouring knowledge-based production and services.
Not far from here, the so-called Aspanggründe site formerly owned by the Austrian Federal Railways offers 22 hectares for a mixed-use urban development project. The master-plan for this project has been drawn up by Norman Foster.
In all, a private investment volume of at least ATS 14.5 billion (Euro 1.05 billion) is expected for the next 15 years for the Erdberger Mais area.