While determining the world's tallest structure has generally been straightforward, the definition of the world's tallest building or the world's tallest tower is less clear. The disputes generally centre on what should be counted as a building or a tower, and what is being measured.
In terms of absolute height, the tallest structure is currently the Burj Dubai, although it does not currently hold the official title of "Tallest Building in the World" until the building is officially opened. The current official holder of the "Tallest Building in the World" is held by Taipei 101. In addition, there are dozens of radio and television broadcasting towers which measure over 600 metres (about 2,000 feet) in height. There is, however, some debate about:
whether structures under construction should be included in the list
whether structures rising out of water should have their below-water height included.
For towers, there is debate over:
whether guy-wire-supported structures should be counted
For buildings, there is debate over:
whether communication towers with observation galleries should be considered habitable buildings.
whether only habitable height is considered.
whether roof-top antennas should be considered towards height of buildings; with particular interest in whether components that look like spires can be either classified as antennas or architectural detail.
The Council on Tall Buildings and Urban Habitat, the organization that determines the title of the "World’s Tallest Building," recognizes a building only if at least fifty percent of its height is made up of floor plates containing habitable floor area. Structures that do not meet this criterion, such as the CN Tower, are defined as "towers."
Burj Dubai (Arabic: برج دبي "Dubai Tower") is a supertall skyscraper under construction in the Downtown Burj Dubai district of Dubai, United Arab Emirates, and is the tallest man-made structure ever built, despite being incomplete. Construction began on 21 September 2004, and the tower is expected to be completed and ready for occupancy by September 2009.
The building is part of the 2 km2 (0.8 sq mi) development called "Downtown Burj Dubai" at the "First Interchange" along Sheikh Zayed Road at Financial Centre Road (previously known as Doha Street). The tower's architect is Adrian Smith who worked with Skidmore, Owings and Merrill (SOM) until 2006. The architecture and engineering firm SOM is in charge of the project. The primary builders are Samsung Engineering & Construction and Besix along with Arabtec. Turner Construction Company was chosen as the construction manager.
The total budget for the Burj Dubai project is about US$4.1 billion and for the entire new 'Downtown Dubai', US$20 billion Mohamed Ali Alabbar, the CEO of Emaar Properties, speaking at the Council on Tall Buildings and Urban Habitat 8th World Congress, said that the price of office space at Burj Dubai had reached $4,000 per sq ft (over $43,000 per sq m) and that the Armani Residences, also in Burj Dubai, were selling for US$3,500 per sq ft (over $37,500 per sq m).