In the 1960's for a lot of architects and urban designers, megastructures were the answer to the question left unanswered by the functionalist, modernist city: how to adapt a building (or a city) to unpredictable growth and change. In a way megastructures were the first examples of time-based urbanism. Megastructures were buildings at the scale of a city. In 1964 the Japanese architect Fumihiko Maki defined a megastructure as 'a large frame in which all the functions of a city or part of a city are housed. It has been made possible by present day technology. In a sense it is a man-made feature of the landscape. It is the great hill on which Italian towns are build.' From this definition two main types of megastructures seem to emerge. On the one hand the more or less naturally grown cluster (the Italian hill town) and on the other hand a more technological idea of a structural frame that 'houses a city'. Maybe a structural frame that 'accommodates'; or 'enables' a city would be more to the point, because it leaves the structure open to unforeseen future changes. This last type was also defined by Kenzo Tange who proposed 'a mass human-scale form which includes a Mega-form, and discrete, rapidly changing functional units which fit within a larger framework,' 1)
It was especially this last type, in which a more or less fixed in time, load bearing structural frame was combined with a changeable and adaptable set of units and functions, which was explored in many design proposals during the sixties. In Europe both architect Yona Friedman and situationist artist Constant Nieuwenhuis proposed large spatial frameworks that would rise above the existing cities. They could be explored and inhabited by either self-builders (Friedmans Citee Spatiale) or by free roaming 'homo ludens' (Constants New Babylon). Besides the split between a structural framework and a loose infill, many - although not Friedmans and Constants - megastructures showed a linear organization that combined infrastructure (roads, walkways, sometimes services) with a set of loadbearing structures at regular intervals. Historical examples of these mega(infra)structures are the medieval street/ bridge Ponte Vecchio in Florence and Le Corbusiers plan Obus of the 1930's.
Not many megastructures were build. A modest example is Cumbernauld (Scotland), but this is hardly considered a success. In a way, the Dutch structuralist designs, like the Kasbah of Piet Blom and the like, could be considered megastructures, but they lack the grandiose scale of the megastructure as described above. Also the large linear megaforms of architects like Bakema and Kenzo Tange, or Ralph Erskines Bykerwall, were certainly mega, but hardly adaptable to change. In fact, megastructures only flourished during the world expo of 1967 in Montreal. Several exhibition buildings like the theme pavilion 'Man the Producer' could be considered megastructural. This is certainly the case for Moshe Safdies housing units Habitat, that combined a concrete structural A-frame with housing cells.
During the sixties Archigram explored the possibilities of a megastructure in techno-pop extravaganza. But the idea slowly reached the end of its life as a designfashion by the early seventies. In fact the deadpan, mirror glass modernist proposal to span the whole earth with a Continuous Monument by Italian radical architects of Superstudio could be considered as the finale.
Although the conquest of the city by megastructures failed, it must be said that architecture and urbanism have not come up with better proposals to accommodate growth and change.
Reyner Banham: 'Megastructure, Urban Futures of the Recent Past' London 1976