Construction began in September 2004, and the tower was officially opened on January 4, 2010. Estimated construction costs were US$1.5 billion requiring 22 million man-hours.No matter how you measure it, the Burj Khalifa is the tallest man-made structure on Earth. The developer, Emaar Properties, wanted the tower to be the world’s largest building according to all four criteria set out by the Chicago-based Council on Tall Buildings and Urban Habitat. These criteria include height of the structural top of the building, its highest occupied floor, height to the top of the roof and to the tip of the building’s spire or flagpole. The official height, which was a closely guarded secret during construction, was announced during the official opening as 2716.5 ft (828 m).