The Tallest Building Ever

A construction corporation in Japan has unveiled designs for a new building, called the X-Seed 4000, that would rise to 13,000 feet (the Sears Tower is 1700 feet) and would house one-million people. Would such a think be possible? I think we've learned by now there's nothing man hasn't been able to engineer. However, the cost of such a structure would be about $1-trillion American. Whoa. (Hat tip: Hot Air)