BURJ DUBAILocation: Dubai, United Arab EmiratesPrice Tag: Approximately $1 billionCompletion Date: 2007Estimated Height: 2950 feetTallest building one-upmanship seems to erupt every 30 to 40 years. In 1930s New York the Chrysler Building battled with the Empire State Building for the world title. In the early ’70s, the World Trade Center and Sears Tower duked it out. Malaysia took the fight overseas in 1998, when its 1483-ft. Petronas Towers overtook the Sears Tower as the world’s tallest building (unless you count the Chicago building’s highest antenna – a point of contention in some circles), only to be bested six years later by Taiwan’s 1671-ft. Taipei 101. Now on deck: Dubai’s 2950-ft. Burj Dubai, slated for completion in 2009. Wary of competitors, its builders are keeping their exact plans a secret; the top of the tower will reportedly be a steel-frame structure that can be expanded upward to defeat any late-breaking challenges. The final height could be as much as 3084 ft., or more than half a mile.Sizing Up: Towers>Burj DubaiA side-by-side comparison with some of the world’s other great towers. bgcolor="#ed1c24" style=“font-color:#ffffff; padding:2px;">Petronas Towers Location: Kuala Lumpur, Malaysia Height: 1483 feet Stories: 88 Completed: 1998 bgcolor="#ed1c24” style=“font-color:#ffffff; padding:2px;">Taipei 101 Location: Taipei, Taiwan Height: 1671 feet Stories: 101 Completed: 2001 bgcolor="#ed1c24” style=“font-color:#ffffff; padding:2px;">Sears Tower Location: Chicago Height: 1451 feet without antenna; 1703 feet with antenna Completed: 1973Jeff WiseJeff Wise is a New York-based science journalist specializing in aviation and psychology. He is the author of The Plane That Wasn’t There: Why We Haven’t Found MH370.