Tallest building in the world

On 21 July Taipei 101 was overtaken in height by the Buji in Duibai upon the completion of that building's 141st floor.

It has been hailed as one of the Seven New Wonders of the World (Newsweek magazine, 2006) and Seven Wonders of Engineering (Discovery Channel, 2005). The building serves as an icon of Taipei and Taiwan as a whole.

Is Taipei Tower the World's Tallest Building?
ANSWER : Yes, if you include the spire.

Anyway according to Jackie Craven (a widely published writer who specializes in architecture) - It depends on who does the measuring! Haha! Got you!

Skyscraper buffs disagree on whether features like flagpoles, antennas, and spires should be included when measuring building height.
Also under dispute is the question of what, exactly, constitutes a building. Technically, observation towers and communications towers are considered structures, not buildings, because they are not habitable. They do not have residential or office space.
Soaring 509 meters (1,670 feet), Taipei 101 in Taipei, Taiwan appears to be the world's tallest building. But the Taipei 101 Tower's massive 60-foot spire contributes to much of that height.

Earthquake Safety: Designing a building this large presented unique challenges because Twaiwan is subject to typhoons and earthquakes. To counter movement, a tuned mass damper system has been incorporated into the structure. The 800-metric ton (1,764,000 lbs.), spherical steel mass is located on level 88 and will be visible from the restaurant and observation decks. The system transfers the energy from the building to the swinging sphere, providing a stabilizing force.