It was the 1960s, just when the Smithsons were writing, that conservation emerged in Britain as a mainstream aspect of architecture, introducing precisely those issues about social purpose, urbanism and ecology that were central to architecture’s participation in the counterculture and its resistance to global capitalism. The Heroic Period of Conservation reveals the significance of conservation in British architectural and cultural history of the last fifty years, recapturing a valuable legacy that is now once more under threat.