It takes 3 years to build a supertall in China (in Beijing its 1 and a half years), just over a year to build a skyscraper. A high spec highrise can be constructed in a few months.
This is because of the 24 hr night and day crews, and the army of workers, its the fastest building rates in the world.
The Beijing Capital Airport is in a 500 sq. mile complex with a terminal that is the worlds biggest building by floor space (10.6 million sq. ft) - 17% bigger than all the 5 terminals in London Heathrow put together, and designed to hold 150 jumbo jets at any one time. It took only 4 years to complete from drawing to opening ceremony, thanks to a construction army of 50,000:
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