do you know where in the world the tallest building is ?

It depends on which definition of "tallest" you use. Burj Dubai is the tallest structure ever built, but you can still call one of the buildings below the tallest completed building or structure.

Skyscraper (under construction): Burj Dubai, UAE, Dubai, 707 m (2320 ft)

Guyed Mast: KVLY-TV mast, US, Blanchard, N.D., 628.8 m (2063 ft)

Concrete Tower: CN Tower, Canada, Toronto, 553.3 m (1815 ft)

Skyscraper (to top of antenna): Sears Tower, US, Chicago, 527.3 m (1730 ft)

Skyscraper (to top of spire): Taipei 101, Taiwan, Taipei, 509.2 m (1671 ft)

Skyscraper (to top of roof): Shanghai World Financial Center, China, Shanghai, 492 m (1614 ft)

The height that Burj Dubai will attain when it's completed hasn't been revealed, due to competition among the other "tallest buildings." Since you said "building" the CN Tower in Toronto definitely doesn't apply. It's the tallest completed free standing structure. The mast in ND is the tallest completed structure, but it isn't free-standing, because it's supported by guy wires. With the three buildings listed last it comes down to: does the antenna count? If not the antenna, then how about the spire? If neither of those count and you just consider the top of the roof itself to count, it's the Shangai World Financial Center.

Read more about Burj Dubai:

http://en.wikipedia.org/wiki/Burj_Dubai

The Burj Dubai is the tallest shape interior the international and may be the tallest construction as quickly because it incredibly is done (that's not counted till it incredibly is done) in 2009. There are plans already underway for an excellent taller skyscraper in Dubai, alongside with countless different tall structures international, although in many circumstances the final height of those is saved secret to offer up different homes beating them. the final height of the Burj Dubai remains no longer publicly time-honored.

It is in Taipei, Taiwan. It is called Taipei 101. The building, designed by C.Y. Lee & partners and constructed primarily by KTRT Joint Venture and Samsung Engineering & Construction, is the world's tallest completed skyscraper according to the CTBUH - the arbiter of tall building height.

Taipei 101 has 101 stories above ground and five underground. Upon its completion Taipei 101 claimed the official records for:

* Ground to highest architectural structure (spire): 509.2 metres (1,670.60 ft). Previously held by the Petronas Towers 452 m (1,483 ft).

* Ground to roof: 449.2 m (1,473.75 ft). Formerly held by the Sears Tower 442 m (1,450 ft).

* Ground to highest occupied floor: 439.2 m (1,440.94 ft). Formerly held by the Sears Tower 412.4 m (1,353 ft).

* Fastest ascending elevator speed: 16.83 m/s (55.22 ft/s) (60.6 km/h, 37.7 mi/h).

* Largest countdown clock: On display every New Year's Eve.

The record for greatest height from ground to pinnacle remains with the Sears Tower in Chicago (USA): 527 m (1,729 ft).

Taipei 101 was the first building in the world to break the half-kilometer mark in height. It was the first "world's tallest building" to be constructed in the new millennium.

Taipei 101 was overtaken in height on July 21, 2007 by the Burj Dubai in Dubai, UAE, upon the completion of that building's 141st floor. The title of "world's tallest building" still rests with Taipei 101, though, as international architectural standards define a "building" as a structure capable of being fully occupied. The Burj Dubai is on course to claim the title once its construction is finished, expected in September 2009.

I've been there and it's beautiful.

Dubai

Toronto.