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Burj Dubai in Dubai, United Arab Emirates is the world's tallest man-made structure in history. It was topped-out at 818 m (2,684 ft) on 17 January 2009.

Although 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 centre on what should be counted as a building or a tower, and what is being measured.

In terms of absolute height, the tallest structure is the Burj Dubai, although it will not hold the official title of "Tallest Building in the World" until the building is officially opened on 4 January 2010. The official holder of the "Tallest Building in the World" is held by Taipei 101. In addition, there are dozens of radio and television broadcasting towers which measure over 600 metres (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 a debate over:

• whether guy-wire-supported structures should be counted

For buildings, there is debate over:

• whether only habitable height is considered.
• whether communication towers with observation galleries should be considered "habitable" in this sense.
• 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.

The Council on Tall Buildings and Urban Habitat, the organization that determines the title of the "World’s Tallest Building," recognizes a building only if at least fifty percent of its height is made up of floor plates containing habitable floor area.^[1] Structures that do not meet this criterion, such as the CN Tower, are defined as "towers."

[edit] Tallest structures

KVLY-TV mast, the height record holder from 1963–1974 and 1991–2008.

The CN Tower in Toronto, Ontario was the world's tallest freestanding structure on land from 1975 until Burj Dubai surpassed it in 2007. At 553.33 m (1,815 ft), it remains the world's tallest completed man made structure.

The tallest man-made structure is Burj Dubai, a skyscraper under construction in Dubai that reached 818 m (2,684 ft) in height on 17 January 2009.^[2] By 7 April 2008 it had been built higher than the KVLY-TV mast in North Dakota, USA, which is still the tallest completed structure at 628.8 m (2,063 ft).^[3] That September it officially surpassed Poland's 646.38 m (2,121 ft) Warsaw radio mast, which stood from 1974 to 1991, to become the tallest structure ever built. Guyed lattice towers such as these masts had held the world height record since 1954.

The CN Tower in Toronto, Ontario, Canada, standing at 553.3 m (1,815 ft), is the world's tallest completed freestanding structure on land. Opened in 1976, it was surpassed in height by the rising Burj Dubai on September 12, 2007.^[4][5][6] It has the world's second highest public observation deck at 446.5 m (1,465 ft).

The Petronius Platform stands 610 m (2,001 ft) off the sea floor leading some, including Guinness World Records 2007, to claim it as the tallest freestanding structure in the world. However, it is debated whether underwater height should be discounted in the same manner as height below grade is ignored on buildings. The Troll A platform is 472 m (1,549 ft), without any part of that height being supported by wires. The tension-leg type of oil platform has even greater below-water heights with several examples more than 1,000 metres (3,300 ft) deep. However, these platforms are not considered constant structures as the vast majority of their height is made up of the length of the tendons attaching the floating platforms to the sea floor. Despite this, Guinness World Records 2009 listed the Ursa tension leg platform as the tallest structure in the world with a total height of 1,306 m (4,285 feet).

Taipei 101 in Taipei, Taiwan is the world's tallest inhabited building in only one of the four main categories that are commonly measured: at 509.2 m (1,671 ft) as measured to its architectural height (spire). Its roof height 449.2 m (1,474 ft) and highest occupied floor 439.2 m (1,441 ft) have recently been overtaken by the Shanghai World Financial Center (roof height 487 m (1,598 ft); highest occupied floor 474 m (1,555 ft)). Willis Tower (formerly Sears Tower) is highest in the final category: the greatest height to top of antenna of any building in the world at 527.3 m (1,730 ft).

On its completion, projected for late 2009, Burj Dubai will break the height record in all four categories for completed buildings by a wide margin. The Shanghai World Financial Center has the world's highest roof, highest occupied floor, and the world's highest public observation deck at 474.2 m (1,556 ft). It will retain the latter record after the completion of Burj Dubai, as Burj Dubai's observation deck will be at 442 m (1,450 ft).

[edit] Tallest structure by category

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Due to the disagreements over how to measure height 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 Willis Tower (formerly Sears Tower) is not considered part of its architectural height, while the spires on top of the Petronas Twin Towers are counted.

[edit] Tallest destroyed structures by category, not surpassed by existing structures

There are some destroyed architectural structures which were taller than the tallest existing structure of their type.

[edit] Tallest building by function

* Mixed-Use is defined as having three or more RE uses (such as retail, office, hotel, etc.) that are physically and functionally integrated in a single property and are mutually supporting.^[10]

** As Burj Dubai is still under construction and not yet inhabitable, it does not serve a specific function. Upon completion, it will serve as a mixed use building.

[edit] Tallest buildings

Burj Dubai compared to some other well-known tall structures.

Up until 1998 the tallest building status was essentially uncontested. Counting buildings as structures with floors throughout, and with antenna masts excluded, Sears Tower (now Willis 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 metres higher than the roof of Willis Tower. Excluding the spire, the Petronas Towers are not taller than Willis Tower. At their convention in Chicago, the Council on Tall Buildings and Urban Habitat (CTBUH) reduced Willis 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:^[11]

1. Height to Architectural Top (including spires and pinnacles, but not antennas, masts or flagpoles). This measurement is the most widely utilized and is used to define the rankings of the 100 Tallest Buildings in the World.
2. Highest Occupied Floor
3. Height to Top of Roof (omitted from criteria in November 2009^[12])
4. Height to Tip

The height is measured from the level of the lowest, significant, open-air, pedestrian entrance. At the time, the Sears Tower held first place in the second and third categories, the Petronas Towers 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, 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 Burj Dubai had surpassed Taipei 101 in height, reaching 512 m (1,680 ft). Burj Dubai was topped-out in early 2009 but is not yet completed.

Today, Taipei 101 leads in the first category with 509 m (1,670 ft), but has been surpassed in the second two categories by the Shanghai World Financial Center whose roof height is 492 m (1,610 ft) and whose highest occupied floor is at 474 m (1,560 ft). Before either of these buildings were completed, the first category was held by the Petronas Twin Towers with 452 m (1,480 ft), and before that by Willis Tower with 442 m (1,450 ft). The second and third categories were held by Willis Tower, with 412 m (1,350 ft) and 442 m (1,450 ft) respectively.

Willis Tower still leads in the fourth category with 527 m (1,730 ft), 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 World Trade Center's destruction in 2001. Its antenna mast included, One World Trade Center measured 526 m (1,730 ft). 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]}

Structures such as the CN Tower, the Ostankino Tower and the Oriental Pearl Tower are excluded from these categories because they are not "habitable buildings", which are defined as frame structures made with floors and walls throughout.^[1]

[edit] History of record holders in each CTBUH category

[edit] World's tallest freestanding structure on land

Freestanding structures include observation towers, monuments and other structures not generally considered to be "Habitable buildings", but excludes supported structures such as guyed masts and ocean drilling platforms. (See also history of tallest skyscrapers.)

The world's tallest freestanding structure on land is defined as the tallest self-supporting man-made structure that stands above ground. This definition is different from that of world's tallest building or world's tallest structure based on the percent of the structure that is occupied and whether or not it is self-supporting or supported by exterior cables. Likewise, this definition does not count structures that are built underground or on the seabed, such as the Petronius Platform in the Gulf of Mexico. Visit world's tallest structure by category for a list of various other definitions.

As of 12 May 2008, the tallest freestanding structure on land is the Burj Dubai in Dubai, United Arab Emirates. The building, which now stands at 818 m (2,680 ft), surpassed the height of the previous record holder, the 553.3 m (1,815 ft) CN Tower in Toronto, Ontario, on September 12, 2007. It is scheduled to be completed in 2009, and was topped out at 818 m (2,684 ft) in January 2009.^[2]

[edit] History

The following is a list of structures that have held the title as the tallest freestanding structure on land. (See also Timeline of three tallest structures in the world until Empire State Building).

Graph of height in feet since 1874

Diagram of the Principal High Buildings of the Old World, 1884.

Notable mentions include the Pharos (lighthouse) of Alexandria, built in the third century BC, and estimated between 115 to 135 m (383–440 ft). It was the world's tallest non-pyramidal building for many centuries. Another notable mention includes the Jetavanaramaya stupa in Anuradhapura, Sri Lanka, which was built in the third century, and was similarly tall at 122 m (400 ft). These were both the world's tallest or second tallest non-pyramidal buildings for over a thousand years.

The tallest secular building between the collapse of the Pharos and the erection of the Washington Monument may have been the Torre del Mangia in Siena, which is 102 m tall, and was constructed in the first half of the fourteenth century, and the 97 m tall Torre degli Asinelli in Bologna, also Italy, built between 1109 and 1119.

[edit] World's highest observation deck

Timeline of development of world's highest observation deck since inauguration of Eiffel Tower.

Higher observation decks have existed on mountain peaks or cliffs, rather than on tall structures. For example, the Royal Gorge Bridge in Cañon City, Colorado, USA, was constructed in 1929 spanning the Royal Gorge at a height of 321 m (1095 ft.) above the Arkansas River.

[edit] Timeline of guyed structures on land

As most of the tallest structures are guyed masts and the absolute height record of architectural structures on land is since 1954 kept by them, here is a timeline of world's tallest guyed masts, since the beginning of radio technology.

As many large guyed masts were destroyed at the end of World War II, the dates for the years between 1945 and 1950 may be incorrect. If Wusung Radio Tower survived World War II, it was the tallest guyed structure shortly after World War II.

[edit] Tallest structures, freestanding structures, and buildings

See also: Timeline of three tallest structures in the world

The list categories are:

• The structures (supported) list uses pinnacle height and includes architectural structures of any type that might use some external support constructions like cables and are fully built in air. Only the three tallest are listed, as more than fifty US TV masts have stated heights of 600-610m (1969–2000 ft).
• The structures (media supported) list uses pinnacle height and includes architectural structures of any type that are not totally built in the air but are using support from other, denser media like salt water. All structures greater than 500 m (1,640 ft) are listed.
• The freestanding structures list uses pinnacle height and includes structures over 400 m (1,312 ft) that do not use guy-wires or other external supports. This means truly free standing on its own or, in similar sense, non-supported structures.
• The building list uses architectural height (excluding antennas) and includes only buildings, defined as consisting of habitable floors. Both of these follow CTBUH guidelines. All supertall buildings (300 m and higher) are listed.

Notes:

• Seven buildings appear on the freestanding structures category list with different heights than of another category. This is due to the different measurement specifications of those lists.
• Only current heights and where reasonable target heights are listed. Historical heights of structures that e.g. did collapse are excluded.

Source: Emporis

[edit] Under construction

Numerous supertall skyscrapers are in various stages of proposal, planning, or construction. Each of the following are under construction and, depending on the order of completion, could become the world's tallest building or structure in at least one category:

• Burj Dubai , under construction in Dubai, UAE, is topped-out at 818 m (2,684 ft) with 160 floors. It is taller than the CN Tower, the tallest completed freestanding structure. It became the tallest manmade structure of any kind in history when it passed the Warsaw radio mast in September 2008. Construction began in September 2004 and completion is expected in January 2010.
• The Digital Media City Landmark Building, under construction in Digital Media City, Seoul in South Korea, is expected to be 640 m (2,100 ft) tall and have 133 floors. If completed, it would be the second tallest building in the world with the tallest observatory and hotels in the world. Construction began in October 2009 and completion is expected in April 2015.
• The Tokyo Sky Tree under construction in Tokyo's Sumida district, is expected to be 634m (2,080 ft) tall. It will be a broadcasting tower to replace the old Tokyo Tower. Construction began in 2008 and completion is expected in 2011, with public access in the spring of 2012.
• The Shanghai Tower, under construction in Shanghai, next to the Shanghai World Financial Center and the Jin Mao Building, is expected to be 632m (2,073 ft). It will be the second tallest building in the world. Completion is expected in 2014.
• The Pentominium, under construction in Dubai, is expected to be 618 m (2,028 ft) tall and have 120 floors. If completed, it would be the tallest all-residential building in the world. Construction began in 2007 and completion is expected in 2011.
• The Russia Tower, was under construction in Moscow's International Business Centre. It was expected to be 612.2 m (2,009 ft) tall and have 118 floors; making it the tallest building in Europe. Construction began in September 2007 and completion was expected in 2012, however, construction was halted in November 2008 due to financial difficulties and it is now unlikely to be completed.
• Incheon Tower is a 151-floor, 610 metres (2,000 ft) twin tower under construction in Incheon, South Korea. If completed, it will stand as the tallest twin towers in the world, surpassing the Petronas Twin Towers. It is estimated to be completed in 2012.
• The Guangzhou TV & Sightseeing Tower, under construction in Guangzhou, China, is topped-out at 610.0 m (2,001 ft). Construction began in November 2005 and completion is expected in 2009.
• The Chicago Spire (formerly Fordham Spire), under construction in Chicago, is expected to be 609.6 m (2,000 ft) and have 150 floors. If completed, it would surpass the CN Tower as the tallest freestanding building in North America,^[16] and would be the second tallest all-residential building in the world (behind the aforementioned Pentominium). Construction began in June 2007 and completion is expected in early 2012, however, construction is on hold.^[17]
• The Abraj Al Bait Towers are under construction in Mecca, Saudi Arabia. The tallest tower is expected to be 595 m (1,952 ft) tall when completed in 2010, becoming second-tallest building in the world when completed. It will also be the largest building in the world with a floor area of 1,500,000 m² (16,137,600 sq ft) and the tallest hotel in the world.
• The Jakarta Tower (Menara Jakarta) is on-hold in Jakarta, Indonesia. It is expected to be 558 m (1,831 ft) tall up to the antenna, thus may be tallest concrete tower. It is expected to be completed in 2011.
• The Federation Tower East, under construction in Moscow's International Business Centre, is expected to be 506 m (1,660 ft) tall (to the tip of the spire) and have 93 floors. If completed, it would become the tallest building in Europe. Construction began in 2003 and completion is expected in 2009.

[edit] Proposed

Many proposed structures have not yet been built, and many probably never will be built. See proposed tall buildings and structures for structures that have been or are being proposed.

[edit] See also

• List of tallest buildings in the world
• List of tallest structures in the world
• List of tallest freestanding structures in the world
• List of towers
• List of architects of supertall buildings

[edit] References

[edit] External links

• Collection of many record holders on Skyscraperpage
• FactMonster.com