| X-Seed 4000 | |
| Native Name: | X-Sen Shushi 7000 |
| Native Name Lang: | Japanese |
| Status: | Proposed |
| Location: | Tokyo, Japan |
| Floor Count: | 700 |
| Cost: | 900B to 1.7T |
| Building Type: | Mixed use |
| Roof: | 40000NaN0 |
| Developer: | Taisei Corporation |
The X-Seed 4000 was a concept for a megatall skyscraper.[1] Its proposed 4km (02miles) height, 6adj=midNaNadj=mid sea-base, and 800-floor capacity could accommodate 500,000-1,000,000 inhabitants. This structure would have been 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.[2] [3] 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."[4]
Unlike conventional skyscrapers, to remain habitable the X-Seed 4000 would have been 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 called for the use of solar power to maintain internal environmental conditions.[1] 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 have been vulnerable to earthquakes and tsunamis.
A sea-based location and a Mount Fuji shape were some of this building's other major design features—Mount Fuji itself is high, making it shorter than the X-Seed 4000.
The X-Seed 4000 was 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, if built, could be in the top five human-made structures are the Ultima Tower of in San Francisco, Dubai City Tower of and the Bionic Tower of in either Hong Kong or Shanghai.