In the early 1960s, the avant-garde architectural group - Archigram - set out to find hypothetical ways of creating alternative buildings and cities for people to live and work in.
Their ultra-modern visions drew inspiration from modular technology and early space capsules - as well as the natural environment.
One of our guest editors, architect Zaha Hadid, wanted to look back at Archigram's visions. She invited one of its members, Sir Peter Cook, to explain some of his designs - including one that became a reality.
Click 'show captions' for image information. Music: Imagination Horizon, composed by Paul Pritchard. Slideshow by Paul Kerley. Publication date 2 January 2009.