Transgressing the distinct boundaries of architecture and urbanism, Berlin Free University is a unique imagination of what a building might be - a building designed to function as a piece of the city, adapting to the needs of its users while generating opportunities for social interaction. The university offers a window into the politicised and optimistic discourse of the 1960s and 1970s, but it also illuminates contemporary debates around large projects of infrastructure and public space. It is, in the words of Peter Smithson, 'one of the two critical building-events of the second half of this century'.