Perhaps you have wondered why the shapes of buildings seem to be getting more complex. Conceivably, it could be nothing more profound than an arbitrary flicker of architectural fashion. But it is worth asking whether the difference between, say, Frank Gehry's Bilbao Guggenheim and the characteristically rectangular slabs and towers of the late 20th century is due to something more fundamental? Does the curved shape of London's Swiss Re Building, the twisted profile of New York's proposed Freedom Tower, or the non-repetitive roof structure of the British Museum courtyard represent some significant change in the conditions of production of architecture?