The X-Seed 4000 was a concept megatall skyscraper. Its proposed height, sea-base, and 800-floor capacity could accommodate 500,000-1,000,000 inhabitants. This structure would be composed of over 3,000,000 tons of steel. It was designed for Tokyo, Japan by the Taisei Corporation in 1995 as a futuristic environment combining ultra-modern and technological living and interaction with wildlife and nature. Methods of transportation within the X-seed would most likely include Maglev trains. Georges Binder, managing director of Buildings & Data, a firm which compiles data banks on buildings worldwide, said the X-Seed 4000 "is never meant to be built . . . The purpose of the plan was to earn some recognition for the firm, and it worked." Unlike conventional skyscrapers, to remain habitable the X-Seed 4000 would be forced to actively protect its occupants from considerable internal air pressure and external air pressure gradations and weather fluctuations that its massive elevation would cause. Its design calls for the use of solar power to maintain internal environmental conditions. As the proposed site for the structure is located in the Pacific Ring of Fire, the most active volcano range in the world, the X-Seed 4000 would be vulnerable to earthquakes and tsunamis. A sea-based location and a Mount Fuji shape are some of this building's other major design features—the real Mount Fuji is land-based and is high, making it shorter than the X-Seed 4000. The X-Seed 4000 is projected to be twice the height of the Shimizu Mega-City Pyramid at . The Shimizu Mega-City Pyramid (also planned for Tokyo, Japan) faces most of the same problems as the X-Seed. Other projects that may be in the top five humanmade structures are the Ultima Tower of in San Francisco, Dubai City Tower of and the Bionic Tower of in either Hong Kong or Shanghai. See also List of visionary tall buildings and structures List of tallest buildings and structures in the world List of tallest structures in Japan List of records of Japan References External links Emporis.com Reference Skyscrapers in Tokyo Unbuilt buildings and structures in Japan Megastructures Unbuilt skyscrapers