Friday, May 2, 2008

List of tallest buildings and structures in the world



List of tallest buildings and structures in the world


While determining the world's tallest structure has generally been straightforward, the definition of the world's tallest building or the world's tallest tower is less clear. The disputes generally center on what should be counted as a building or a tower, and what is being measured.
In terms of absolute height, the tallest structures are currently the dozens of radio and television broadcasting towers which measure over 600 meters (about 2,000 feet) in height. There is, however, some debate about:
whether structures under construction should be included in the list
whether structures rising out of water should have their below-water height included.
For towers, there is debate over:
whether guy-wire-supported structures should be counted
For buildings, there is debate over:
whether communication towers with observation galleries should be considered habitable buildings.
whether only habitable height is considered.
whether roof-top antennas should be considered towards height of buildings; with particular interest in whether components that look like spires can be either classified as antennas or architectural detail.
These debates will likely lose some relevance in 2009, as the Burj Dubai, a building currently under construction in Dubai, United Arab Emirates, has already become the world's tallest man-made structure.


Tallest structures


Main article: List of tallest structures in the world

KVLY-TV mast

The CN Tower in Toronto, Ontario was the world's tallest freestanding structure on land from 1975 until the Burj Dubai surpassed it in 2007, rising 553.33 m (1,815 ft). It is currently the world's tallest completed freestanding structure on land.
The tallest man-made structure is the Burj Dubai, a skyscaper still under construction in Dubai, that has reached 629 m (2,064 ft) in height as of April 7, 2008.
The CN Tower in Toronto, Ontario, Canada, standing at 553.3 m (1,815 ft), was the world's tallest freestanding structure on land from 1976 until September 12, 2007, when it was overtaken in height by the rising Burj Dubai.[1] The tower has the world's highest public observation deck at 446.5 m (1,465 ft).
The Petronius Platform stands 610 m (2,001 ft), leading some[who?] to claim it as the tallest freestanding structure in the ocean. However, as this oil and natural gas platform is partially supported by wires, critics[who?] argue that it is not freestanding, and the below-water height should not be counted, in the same manner as underground 'height' is not taken into account in buildings.The Troll A platform is 472 m (1,549 ft), without any part of that height being supported by wires.
Taipei 101 in Taipei, Taiwan is currently the world's tallest inhabited building in three of the four main categories that are commonly measured: at 509.2 m (1,671 ft) as measured to its architectural height (spire) as well as roof height 449.2 m (1,474 ft) and highest occupied floor 439.2 m (1,441 ft). The Sears Tower is highest in the last category: the greatest height to top of antenna of any building in the world at 527.3 m (1,730 ft).
The Burj Dubai, currently under construction, is already the tallest freestanding structure on land. As of 7 April 2008, the tower's developers reported its height to be 629 m (2,064 ft) with 160 completed floors,[2]. On its completion, projected for 2009, it will break the height record in all four categories for completed buildings by a wide margin. While the final height has not been released to the public, Greg Sang, the construction manager, says that the building will rise to a minimum of 700 m (2,297 ft).[3] The developer, Emaar, is keeping structural details secret due to competition for the "world's tallest" with other proposed structures, including the nearby Al Burj.[4] The CN Tower will retain its record of the world's highest observation deck as Burj Dubai's deck will be at 442 m (1,450 ft).[5] The 'Symbol of Dubai' will have more than 160 floors, 56 elevators, apartments, shops, swimming pools, spas and corporate suites.


Tallest structure by category

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Due to the disagreements over how to measure and classify structures, engineers have created various definitions for categories of buildings and other structures. One measure includes the absolute height of a building, another includes only spires and other permanent architectural features, but not antennas. The tradition of including the spire on top of a building and not including the antenna dates back to the rivalry between the Chrysler Building and 40 Wall Street. A modern-day example is that the antenna on top of the Sears tower are not considered part of its architectural height, while the spires on top of the Petronas


Tallest buildings


Main article: List of tallest buildings in the world

Comparison of top skyscrapers with measurements to top of antenna along to the oldest modern one, the Eiffel Tower from 1889

Current skyscrapers compared with notable under construction skyscrapers
Up until 1998 the tallest building status was essentially uncontested. Counting buildings as structures with floors throughout, and with antenna masts excluded, the Sears Tower in Chicago was considered the tallest. When the Petronas Twin Towers in Kuala Lumpur, Malaysia were built, controversy arose because the spire extended nine meters higher than the roof of the Sears Tower. Excluding the spire, the Petronas Towers are not taller than the Sears Tower. At their convention in Chicago, the Council on Tall Buildings and Urban Habitat (CTBUH) reduced the Sears Tower from world's tallest and pronounced it not second tallest, but third, and pronounced Petronas as world's tallest. This action caused a considerable amount of controversy, so CTBUH defined four categories in which the world's tallest building can be measured:
Height to the structural or architectural top (including spires and pinnacles, but not antennas, masts or flagpoles)
Height to the highest occupied floor
Height to the top of the roof
Height to the top of antenna
The height is measured from the pavement level of the main entrance. At the time, the Sears Tower held first place in the second and third categories. Petronas held the first category, and the original World Trade Towers held the fourth. Within months, however, a new antenna mast was placed on the Sears Tower, giving it hold of the fourth category. On April 20, 2004, the Taipei 101 in Taipei, Taiwan, was completed. Its completion gave it the world record for the first three categories. On July 21, 2007 it was announced that the Burj Dubai had surpassed Taipei 101 in height, reaching 512 m (1,680 feet) tall. However Burj Dubai is still under construction.
Today, Taipei 101 leads in the first category with 509 m (1,671 feet); in the second category with an occupied floor at 439 m (1,441 feet); and in the third category with 449 m (1,474 feet). The first category was formerly held by the Petronas Twin Towers with 452 m (1,483 feet), and before that by Sears Tower with 442 m (1,451 feet). The second and third categories were held by the Sears Tower, with 412 m (1,351 feet) and 442 m (1,451 feet) respectively.
The Sears Tower still leads in the fourth category with 527 m (1,729 feet), previously held by the World Trade Center until the extension of the Chicago tower's western broadcast antenna in 2000, over a year prior to the Trade Center's destruction in 2001. Its antenna mast included, 1 World Trade Center measured 526 m (1,727 feet). The World Trade Center became the world's tallest buildings to be destroyed or demolished; indeed, its site entered the record books twice on September 11, 2001, in that category, replacing the Singer Building, which once stood a block from the WTC site.[citation needed]







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