Sky City (Chinese: 天空城市; pinyin: tiānkōng chéngshì), or Sky City One, was an 838-metre-tall (2,749 ft)[7][8][9] planned skyscraper in the city of Changsha, Hunan in south-central China.[10] The prospective builders, Broad Sustainable Building, estimated it would take just 90 days to construct.[11][12] Including the 120 days required for prefabrication before on-site work commenced, the sum of time needed was 210 days.[13] Pre-construction activities were halted in August 2013 after government regulators required additional approvals