The Burj Khalifa (formerly named the Burj Dubai) is a tower 828 m (2,717 ft) tall in the city of Dubai in the United Arab Emirates. It surpasses Toronto's CN Tower (553 metres - 1,824.9 feet) as the world's tallest structure, and is planned to reach over 800 meters. It also had exceeded Taiwan's Taipei 101 which is 508 metres (1,676.4 feet) tall. The building includes private residences, resturants, hotels, and high end hotel suites.
The skyscraper, being built by South Korea's Samsung (which built Petronas Twin Towers and the Taipei 101) and set for completion at the end of next year, is one of several mega projects taking shape in Dubai, which is part of the United Arab Emirates. 
Groundbreaking began on September 21, 2004 and construction was officially finished on October 21, 2009; a time span of just over five years. In a surprise move, the tower was renamed the Burj Khalifa to honor Khalifa bin Zayed Al Nahyan; the president of the United Arab Emirates at it's opening ceremony.
The building houses apartments, hotel rooms, high end hotel suites, mechanical operations, "corporate suites", and rooms for communication and broadcast operations, however there is no conventional AM or FM radio broadcasting at the tower.
The housing bubble
Due to the infamous housing bubble burst in Dubai in 2010, declining demand caused rents in the apartments to decline by 40%. There are 900 apartments in the tower, and approximately 825 were still empty at the time. By October of 2012, Emaar Properties reported that approximately 80% of the apartments were occupied and Dubai is managing a steady recovery.
The total cost of constructing the building is estimated to be a grand total of the equivalent of $1.5 billion American dollars.