The Chinese construction firm Broad Sustainable Building(BSB) has an ambitious plan to build the world's tallest skyscraper, and it looks like they're making progress: the Chinese government has given the go-ahead for BSB to build Sky City, a 220-story, 838.2 meter skyscraper (almost one kilometer tall), the largest in the world. Even crazier, the Chinese firm is trying to build it in just three months and it will be energy efficient, decreasing CO2 emissions from 5.5 tons to just 2 tons per capita. The current record-holder, the Burj Khalifa in Abu Dhabi, was constructed in five years, and even that took some impressive engineering. BSB wants to make Sky City possible by spending four months prefabricating the materials off-site, and then erecting it all over the course of three months, starting this month. When complete, the building will be almost a city: 30,000 people will be able to take 104 elevators or a single 9.6 kilometer ramp that curls through the interior toward a school, hospital, and housing. What is more, the building will be magnitude 9 earthquake resistant. The projected price tag for it all is 6.2 billion rand ($628 million dollars, considerably less than the $1.5 billion dollar price tag of the Burj Khalifa). Watch the building time lapse video in order to form an idea of how these pre-constructed engineering wonder will work.Story by Colin Lecher