Burj Khalifa formerly known as Burj Dubai, is a skyscraper in Dubai, United Arab Emirates, and the tallest man-made structure ever built, at 828 m (2,717 ft). Construction began on 21 September 2004, with the exterior of the structure completed on 1 October 2009. The building officially opened on 4 January 2010.The building is part of the 2 km2 (490-acre) flagship development called Downtown Burj Khalifa at the "First Interchange" along Sheikh Zayed Road, near Dubai's main business district.The tower's architecture and engineering was performed by Skidmore, Owings, and Merrill of Chicago. Adrian Smith, who worked with Skidmore, Owings and Merrill until 2006, was the chief architect and Bill Baker was the chief structural engineer for the project.The primary contractor was Samsung C&T of South Korea, who also built the Taipei 101 and Petronas Twin Towers. Major subcontractors included Belgian group Besix and Arabtec from the UAE. Turner Construction Company was chosen as the construction project manager.Under UAE law, the Contractor and the Engineer of Record are jointly and severally liable for the performance of Burj Khalifa.