Sky City 1000 is a visionary (i.e. not proposed/intended to be built) supertall skyscraper

Skyscraper

A skyscraper is a tall, continuously habitable building of many stories, often designed for office and commercial use. There is no official definition or height above which a building may be classified as a skyscraper...

 in the Tokyo

Tokyo

, ; officially , is one of the 47 prefectures of Japan. Tokyo is the capital of Japan, the center of the Greater Tokyo Area, and the largest metropolitan area of Japan. It is the seat of the Japanese government and the Imperial Palace, and the home of the Japanese Imperial Family...

 metropolitan area, Japan

Japan

Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...

 announced in 1989 during the height of the Japanese asset price bubble

Japanese asset price bubble

The was an economic bubble in Japan from 1986 to 1991, in which real estate and stock prices were greatly inflated. The bubble's collapse lasted for more than a decade with stock prices initially bottoming in 2003, although they would descend even further amidst the global crisis in 2008. The...

.

The plan consists of a building 1000 metres (3,281 ft) tall and 400 m (1,312 ft) wide at the base, and a total floor area of 8 km² (3.1 sq mi). The design, proposed in 1989 by Takenaka Corporation

Takenaka Corporation

is the biggest architecture, engineering, and construction firm in Japan. Its headquarters is in Chūō-ku, Osaka, Osaka Prefecture.The company's website also claims it to be the oldest firm of that type anywhere in the world, since the demise of Kongō Gumi which was substantially older...

, would house between 35,000 and 36,000 full-time residents, as well as 100,000 workers.