Burj Khalifa .. Formerly It known as Burj Dubai . Burj Khalifa has been the world's tallest building since 2010

Srini Just For Your Info
- Wills Tower or Sears Tower . was the world's tallest building from 1974 to 1998.
- Taipei 101 or Taipei World Financial Center, was the world's tallest building from 2004 to 2010.
- The Petronas Towers (also known as the Petronas Twin Towers or KLCC) are skyscrapers and twin towers in Kuala Lumpur, Malaysia. They were the tallest buildings in the world from 1998 to 2004

Willis Tower (formerly named, and still commonly referred to as Sears Tower) is a 108-story, 1451-foot (442 m) skyscraper in Chicago, Illinois.[1] At the time of its completion in 1974, it was the tallest building in the world, surpassing the World Trade Center towers in New York, and it held this rank for nearly 25 years. The Willis Tower is the tallest building in the United States and the fifth-tallest freestanding structure in the world, as well as the fifth tallest building in the world to the roof.

Although Sears' naming rights expired in 2003, the building continued to be called Sears Tower for several years. In March 2009 London-based insurance broker Willis Group Holdings, Ltd., agreed to lease a portion of the building and obtained the building's naming rights.[3] On July 16, 2009, the building was officially renamed Willis Tower

Source: wikipedia

Twin towers?

Burj Khalifa !!

Wills tower

Petrona towers