http://en.wikipedia.org/wiki/Citygate_ecotower
The Citygate Ecotower was a visionary skyscraper that had been designed for London, United Kingdom as a proposal by M3 Architects. It was designed to be an environmentally friendly building and would be clad in photovoltaic cells and have wind turbines on the roof. The location of the tower would be a huge asset to it as it would be located over a large transport interchange (Aldgate High Street).
At 108 floors, 485 metres (1,591 ft) high it would have been the tallest building in the country. It would also have had a mixed use of offices, hotel and apartments.