Behold, the World's Tallest Concept Building (That Of Course Was Never Built)
There are skyscrapers, and then there are skypenetrators. The X-Seed 4000 is one of the latter.
Conceived in the mid-1990s for a site in downtown Tokyo, the 'Seed is an eyeball-sucking ogre of a building (or "hyperbuilding," as these freakishly tall structures are sometimes called). At 800 stories tall, you could practically read a book cover to cover on the elevator ride to the X-Seed's penthouse. The company that planned to build it, Taisei Construction Corporation, never got around to erecting it; however, maybe they didn't want to. An Architectural Record investigation into the current state of the X-Seed quoted one building expert as saying, “It was never meant to be built. The purpose of the plan was to earn some recognition for the firm, and it worked.”
Take note, architecture firms: If you crave attention, just whip up a handful of concept drawings for a tower so tall that people would think you confused "Tokyo" with "NeoTokyo." Giggles and wide-eyed stares are the appropriate response to the X-Seed, which would measure 13,123 feet or 2.5 miles high. (By contrast, the world record-holding Burj Khalifa in Dubai is a shrimp at merely 2,717 feet high.) Perhaps it's best it never saw the light of day, because then the Japanese might have to switch affections away from Mount Fuji to the X-Seed – the hyperbuilding wins out by a margin of 735 feet.
The cloud-poking prong is not only bigger than any skyscraper in existence. It's said to be bigger than any not in existence anywhere but the drawing board. So it's taller than the listing beanstalk of heaven that is the Oakland Eye in the Sky Tower, and taller even than the Ultima Tower, a two-mile-high megastructure that could kill anybody who tried to take the stairs. (Although, I just envisioned a skyscraper in my head, the Metcalfe Tower, that's 13,124 feet tall. Take that, Taisei Construction Corporation!)
So why didn't it get built? The obvious reasons rush to the forefront: Real estate in Tokyo isn't exactly cheap. The base of this abnormally swole tower would eat up blocks and blocks if it was to be stable. And that's another issue: stability. Japan is home to frequent earth-shaking visitors. Would the X-Seed hold up under a magnitude 8, or would it topple like Odin's Jenga set, taking out half the city when it smashes into the ground?
Then there's the issue of how its 1 million inhabitants would get around. People would need maps and some kind of light-rail system for transport if they wanted to get to meetings on time.
While Tokyo will never live under the shadow of this mighty tower, floating around online are some illustrations, apparently devised sometime in the '90s, depicting what it would look like. Here goes: