Broad Sustainable Building (BSB) is attempting to build the world's tallest skyscraper, Sky City, in just 90 days. The Chinese company will hope to begin construction of the skyscraper in the city of Changsa by November 2012. Completing an 838-meter building (the Burj Khalifa is 828 meters) is no small task. Fortunately, BSB is no stranger to working under strict time constraints. The company once built a 15-story building in six days, and a 30-story hotel in 15 days.
The company's secret lies in its prefabrication of nearly every piece of the buildings it erects. It's said that 95 percent of Sky City will be completed before BSB breaks ground. In addition to be being the world's tallest tower, Sky City will also be one of the most sustainable, and is said to use a fifth of the energy of other buildings its size.