Burj Khalifa (Arabic: برج خليفة‎ "Khalifa Tower") known as Burj Dubai prior to its inauguration, is a skyscraper in Dubai, United Arab Emirates, and is currently the tallest structure in the world, at 829.84 m (2,723 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 and is part of the new 2 km2 (490-acre) flagship development called Downtown Dubai The tower's architecture and engineering were performed by Skidmore, Owings and Merrill of Chicago.
The total cost for the project was about US$1.5 billion