The Burj Dubai tower contains 57 elevators, 1,044 apartments, 49 floors of office space and a hotel.
It can be seen from as far as 59 miles away and is estimated to have cost one billion dollars.
While the exact height of the building is under wraps, Emaar, the firm that developed the property, says it exceeds 2,640 feet, putting it far higher than Taiwan's Taipei 101 tower.
"We thought that it would be slightly taller than the existing tallest tower of Taipei 101. (Emaar) kept on asking us to go higher but we didn't know how high we could go," Bill Baker, a partner in Skidmore, Owings and Merrill (SOM), which designed the tower, told the AFP.
"We were able to tune the building like we tune a music instrument. As we went higher and higher and higher, we discovered that by doing that process... we were able to reach heights much higher than we ever thought we could.”
With a new title holder, the tallest building in the United States would drop to fifth place in the world. That would be the Willis Tower, formerly the Sears Tower, in Chicago at 1,389 feet.
The Freedom Tower, planned for the former site of the World Trade Center's Twin Towers in New York City, is expected to rise 1,776 feet. It is due to be completed in 2013.
Property prices in Dubai have dived over 50 percent over the past year and some believe the skyscrpaer will be the last of the giant projects that have brought global fame to Dubai.