The X-Seed 4000 is the largest building ever fully envisioned and would rise 13,000 feet (or 2.5 miles) into the sky over Tokyo while boasting a 6 kilometre wide sea base. It would have 800 floors and could potentially accommodate 500,000 to one million inhabitants. The design was inspired by Mount Fuji.
Now that we’ve fully piqued your curiosity, we have some bad news. The X-Seed 4000 will never be built. It was designed in 1995 by the Japanese construction and development firm, Taisei Corporation, but the purpose of the design was simply to earn recognition for the firm.
Considering the fact that we’re still in awe of the renderings more than fifteen years later, it seems like it worked.
How much would it cost to actually construct this gigantic structure? Estimates range from $327 billion to $981 billion. What’s even wilder is the design team actually took into account the air pressure gradations and intense weather fluctuations that would occur for those inhabiting the upper floors. Sounds like it’s pretty well thought out, now someone just needs close to a trillion dollars to build it.
Here’s a (slightly dated) chart that gives you an idea of the scale of this monster:
Perhaps someday we’ll build a skyscraper of comparable size, but for now we’ll have to be content will our mega tall skyscrapers.