The world's tallest skyscraper in 90 days

According to the builder Sky City  will be the tallest building in the world and will open in March 2013 . It will be located in the Chinese city of Changsha. The skyscraper will have a height of  838 meters  spread over  220 floors and will be built in only 90 days, five plants per day. The building was designed by some of the engineers who worked previously on the skyscraper  Burj Khalifa in Dubai, 828 meters. Construction will start later this month, after Chinese authorities approved the project.  For Sky City building will be used 220,000 tons of steel. The structure will be able to house more than 30,000 people, will feature 104 high speed elevators to move into the skyscraper.  This type of construction is carried out by using a technology modular prefabricateddeveloped by Broad Sustainable Building, a company that has built 20 high structures in China so far.  The Chinese company says it will cost  $ 1,500 per square meter,  compared with the $ 15,000 Burj, all thanks to the prefabricated technology. The company says that the residential area will occupy 83% of the building, while the rest are offices , schools , hospitals, shops and restaurants. They also claim to be able to withstand earthquakes of a magnitude 9.0 degrees and resistance to fire for "up to three hours".