X-Seed 4000: 4,000 Meters Skyscraper With Up to 1,000,000 Resident
According to Wikipedia, The X-Seed 4000 is the tallest building ever fully designed for a building proposal at 4,000 meters high (13,123.2 feet). It would be 6,000 meters in diameter at the base and would contain 800 floors. If built, its likely location would be in Tokyo, Japan. It was designed by the Taisei Construction Corporation as a possible mountain-shaped futuristic environment in which 500,000 to 1,000,000 people could live, purposely combining ultra-modern living with interaction with nature. It will be powered by solar energy, and it will be able to react to the weather conditions outside to keep the light, temperature, and air pressure the same inside. Due to its enormous size, the only place where it was plausible to be built is on the sea. If realized, it would even be taller than Mount Fuji, Japan's tallest mountain, which is 3776 meters high (12,388 ft).
Would Dubai be able to beat this design project? At this point, I will not be surprised to find out one day that there will be an even bigger and taller building to be built in Dubai.
X-Seed 4000 (Wikipedia)
X-Seed 400 (Accelerating Future)
City in a Pyramid (Discovery Channel)