A skyscraper is a tall, continuously habitable building. There is no official definition or height above which a building may clearly be classified as a skyscraper. Most cities define the term empirically; even a building of 80 meters (262 feet) may be considered a skyscraper if it protrudes above its built environment and changes the overall skyline.
Definition
Taipei 101 is the world's tallest completed skyscraper.The word "skyscraper" originally was a nautical term referring to a small triangular sail set above the skysail on a sailing ship. The term was first applied to buildings in the late 19th century as a result of public amazement at the tall buildings being built in Chicago and New York City. The traditional definition of a skyscraper began with the "first skyscraper", Chicago's now demolished ten-storey steel-framed Home Insurance Building (1885).
The structural definition of the word skyscraper was refined later by architectural historians, based on engineering developments of the 1880s that had enabled construction of tall multi-storey buildings. This definition was based on the steel skeleton—-as opposed to constructions of load-bearing masonry, which passed their practical limit in 1891 with Chicago's Monadnock Building. Philadelphia's City Hall, completed in 1901, still holds claim as the world's tallest load-bearing masonry structure at 167 m (548 ft). The steel frame developed in stages of increasing self-sufficiency, with several buildings in Chicago and New York advancing the technology that allowed the steel frame to carry a building on its own. Today, however, many of the tallest skyscrapers are built almost entirely with reinforced concrete.[1] Pumps and storage tanks maintain water pressure at the top of skyscrapers.
A loose convention in the United States and Europe now draws the lower limit of a skyscraper at 150 meters (500 ft).[2] A skyscraper taller than 300 meters (984 ft) may be referred to as supertall. Shorter buildings are still sometimes referred to as skyscrapers if they appear to dominate their surroundings.
The somewhat arbitrary term skyscraper should not be confused with the also ill-defined term high-rise. The Emporis Standards Committee defines a high-rise building as "a multi-story structure between 35-100 meters tall, or a building of unknown height from 12-39 floors"[3] and a skyscraper as "a multi-story building whose architectural height is at least 100 meters."[4] Some structural engineers define a highrise as any vertical construction for which wind is a more significant load factor than earthquake or weight. Note that this criterion fits not only high rises but some other tall structures, such as towers.
The word skyscraper often carries a connotation of pride and achievement. The skyscraper, in name and social function, is a modern expression of the age-old symbol of the world center or axis mundi: a pillar that connects earth to heaven and the four compass directions to one another.[5]
History
Before the 19th century
The Great Pyramid of Giza, circa 2560 BC, was 146 metres tall and its height was unsurpassed until at least the 14th century AD.
The Two Towers of Bologna in the 12th century reached 97.2 metres in height.
The 16th-century city of Shibam consisted entirely of over 500 high-rise tower houses.Modern skyscrapers are built with materials such as steel, glass, reinforced concrete and granite, and routinely utilize mechanical equipment such as water pumps and elevators. Until the 19th century, buildings of over six stories were rare, as having great numbers of stairs to climb was impractical for inhabitants, and water pressure was usually insufficient to supply running water above 50 m (164 ft).
The tallest building in ancient times was the Great Pyramid of Giza in ancient Egypt, which was 146 metres (480 ft) tall and was built in the 26th century BC. Its height was not surpassed for thousands of years, possibly until the 14th century AD with the construction of Lincoln Cathedral (though its height is disputed),[6] which in turn was not surpassed in height until the Washington Monument in 1884. However, being uninhabited buildings, none of these buildings actually complies with the definition of a skyscraper.

High-rise apartment buildings already flourished in classical antiquity: ancient Roman insulae in Rome and other imperial cities reached up to 10 and more stories,[7] some with more than 200 stairs.[8] Several emperors, beginning with Augustus (r. 30 BC-14 AD), attempted to establish limits of 20-25 m for multi-storey buildings, but met with only limited success.[9][10] The lower floors were typically occupied by either shops or wealthy families, while the upper stories were rented out to the lower classes.[7] Surviving Oxyrhynchus Papyri indicate that seven-storey buildings even existed in provincial towns, such as in 3rd century AD Hermopolis in Roman Egypt.[11]

The skylines of many important medieval cities had large numbers of high-rise urban towers. Wealthy families built these towers for defensive purposes and as status symbols. The residential Towers of Bologna in the 12th century, for example, numbered between 80 to 100 at a time, the largest of which (known as the "Two Towers") rise to 97.2 metres (319 ft). In Florence, a law of 1251 decreed that all urban buildings should be reduced to a height of less than 26 m, the regulation immediately put into effect.[12] Even medium-sized towns at the time such as San Gimignano are known to have featured 72 towers up to 51 m height.[12]
The medieval Egyptian city of Fustat housed many high-rise residential buildings, which Al-Muqaddasi in the 10th century described as resembling minarets. Nasir Khusraw in the early 11th century described some of them rising up to 14 stories, with roof gardens on the top floor complete with ox-drawn water wheels for irrigating them.[13] Cairo in the 16th century had high-rise apartment buildings where the two lower floors were for commercial and storage purposes and the multiple stories above them were rented out to tenants.[14] An early example of a city consisting entirely of high-rise housing is the 16th-century city of Shibam in Yemen. Shibam was made up of over 500 tower houses,[15] each one rising 5 to 11 storeys high,[16] with each floor being an apartment occupied by a single family. The city was built in this way in order to protect it from Bedouin attacks.[15] Shibam still has the tallest mudbrick buildings in the world, with many of them over 100 feet (30 m) high.[17]
An early modern example of high-rise housing was in 17th-century Edinburgh, Scotland, where a defensive city wall defined the boundaries of the city. Due to the restricted land area available for development, the houses increased in height instead. Buildings of 11 stories were common, and there are records of buildings as high as 14 stories. Many of the stone-built structures can still be seen today in the old town of Edinburgh. The oldest iron framed building in the world is The Flaxmill (also locally known as the "Maltings"), in Shrewsbury, England. Built in 1797, it is seen as the "grandfather of skyscrapers”, since its fireproof combination of cast iron columns and cast iron beams developed into the modern steel frame that made modern skyscrapers possible. Unfortunately, it lies derelict and needs much investment to keep it standing.

Early skyscrapers
The first skyscraper was the ten-storey Home Insurance Building in Chicago, built in 1884–1885. While its height is not considered very impressive today, it was at that time. The architect, Major William Le Baron Jenney, created the first load-bearing structural frame. In this building, a steel frame supported the entire weight of the walls, instead of load-bearing walls carrying the weight of the building, which was the usual method. This development led to the "Chicago skeleton" form of construction. After Jenney's accomplishment the sky was truly the limit as far as building was concerned.

Sullivan's Wainwright Building in St. Louis, 1891, was the first steel-framed building with soaring vertical bands to emphasize the height of the building, and is, therefore, considered by some to be the first true skyscraper.
Built in 1931, The Empire State Building in New York City is one of the oldest, yet tallest skyscrapers.Most early skyscrapers emerged in the land-strapped areas of Chicago, London, and New York toward the end of the 19th century. A land boom in Melbourne, Australia between 1888-1891 spurred the creation of a significant number of early skyscrapers, though none of these were steel reinforced and few remain today. Height limits and fire restrictions were later introduced. London builders soon found building heights limited due to a complaint from Queen Victoria, rules that continued to exist with few exceptions until the 1950s. Concerns about aesthetics and fire safety had likewise hampered the development of skyscrapers across continental Europe for the first half of the twentieth century (with the notable exceptions of the 26-storey Boerentoren in Antwerp, Belgium, built in 1932, and the 31-storey Torre Piacentini in Genoa, Italy, built in 1940). After an early competition between New York City and Chicago for the world's tallest building, New York took the lead by 1895 with the completion of the American Surety Building, leaving New York with the title of tallest building for many years. New York City developers competed among themselves, with successively taller buildings claiming the title of "world's tallest" in the 1920s and early 1930s, culminating with the completion of the Chrysler Building in 1930 and the Empire State Building in 1931, the world's tallest building for forty years. The first completed World Trade Center tower became the world's tallest building in 1972 for two years. That changed with the completion of the Sears Tower (later renamed the Willis Tower) in Chicago in 1974, which became the world's tallest building for several decades.

Modern skyscrapers
The iconic World Trade Center twin towers were destroyed in 2001.
The Willis Tower in Chicago was the world's tallest building from 1974 to 1998, and remains the tallest in the United States.
The Petronas Twin Towers, the world's tallest twin buildings.
Tower 2 of the International Finance Centre in Hong Kong is one of the 20 tallest buildings in the world.
The Commerzbank Tower in Frankfurt/Germany is the tallest completed skyscraper in the European Union.
30 St Mary Axe in London, United Kingdom is an example of a modern environmentally friendly skyscraper.From the 1930s onwards, skyscrapers also began to appear in Latin America (São Paulo, Caracas, Mexico City) and in Asia (Tokyo, Shanghai, Hong Kong, Manila, Singapore, Mumbai, Jakarta, Kuala Lumpur, Taipei, Bangkok). Immediately after World War II, the Soviet Union planned eight massive skyscrapers dubbed "Stalin Towers" for Moscow; seven of these were eventually built. The rest of Europe also slowly began to permit skyscrapers, starting with Madrid, in Spain, during the 1950s. Finally, skyscrapers also began to be constructed in cities of Africa, the Middle East and Oceania (mainly Australia) from the late 1950s.

In the early 1960s structural engineer Fazlur Khan realized that the rigid steel frame structure that had "dominated tall building design and construction so long was not the only system fitting for tall buildings", marking "the beginning of a new era of skyscraper revolution in terms of multiple structural systems."[18] His central innovation in skyscraper design and construction was the idea of the "tube" structural system, including the "framed tube", "trussed tube", and "bundled tube".[19] These systems allowed far greater economic efficiency,[20] and also allowed efficient skyscrapers to take on various shapes, no longer needing to be box-shaped.[21] Over the next fifteen years, many towers were built by Khan and the "Second Chicago School",[22] including the massive 442-meter (1,451-foot) Willis Tower.[23] Chicago is currently undergoing an epic construction boom that will greatly add to the city's skyline. Since 2000, at least 40 buildings at a minimum of 50 stories high have been built or planned.[24] The Chicago Spire, Trump International Hotel and Tower, Waterview Tower, Mandarin Oriental Tower, 29-39 South LaSalle, Park Michigan, and Aqua are some of the more notable projects currently underway in the city that invented the skyscraper. Chicago, Hong Kong, and New York City, otherwise known as the "the big three," are recognized in most architectural circles as having the most compelling skylines in the world. Other large cities that are currently experiencing major building booms involving skyscrapers include London in the United Kingdom, Shanghai in China, Dubai in the United Arab Emirates, and Miami, which now is third in the United States.[25]

[edit] History of tallest skyscrapers
Main article: History of the tallest buildings in the world
At the beginning of the 20th century, New York City was a center for the Beaux-Arts architectural movement, attracting the talents of such great architects as Stanford White and Carrere and Hastings. As better construction and engineering technology became available as the century progressed, New York and Chicago became the focal point of the competition for the tallest building in the world. Each city's striking skyline has been composed of numerous and varied skyscrapers, many of which are icons of 20th century architecture:

The Flatiron Building, standing 285 ft (87 m) high, was one of the tallest buildings in the city upon its completion in 1902, made possible by its steel skeleton. It was one of the first buildings designed with a steel framework, and to achieve this height with other construction methods of that time would have been very difficult.
The Woolworth Building, a neo-Gothic "Cathedral of Commerce" overlooking City Hall, was designed by Cass Gilbert. At 792 feet (241 m), it became the world's tallest building upon its completion in 1913, an honor it retained until 1930, when it was overtaken by 40 Wall Street.
That same year, the Chrysler Building took the lead as the tallest building in the world, scraping the sky at 1,046 feet (319 m).[26] Designed by William Van Alen, an art deco masterpiece with an exterior crafted of brick,[27] the Chrysler Building continues to be a favorite of New Yorkers to this day.[28]
The Empire State Building, the first building to have more than 100 floors (it has 102), was completed the following year. It was designed by Shreve, Lamb and Harmon in the contemporary Art Deco style. The tower takes its name from the nickname of New York State. Upon its completion in 1931, it took the top spot as tallest building, and at 1,472 feet (448 m) to the very top of the antenna, towered above all other buildings until 1973.
The World Trade Center was completed in 1973 and consisted of two tall towers and several smaller buildings. For a short time, the first of the two towers was the world's tallest building. Upon completion, the towers stood for twenty-eight years, until the September 11, 2001 attacks destroyed the structures. Various governmental entities, financial firms, and law firms called the towers home.
The Willis Tower (formerly Sears Tower) was completed in 1974, one year after the World Trade Center, and surpassed it as the world's tallest building. It was the first building to employ the "bundled tube" structural system, designed by Fazlur Khan.[21] The building was not surpassed in height until the Petronas Towers were constructed in 1998, but remained the tallest in some categories until the Burj Dubai, currently under construction, surpassed it in all categories. It is currently the tallest building in the United States.
Momentum in setting records passed from the United States to other nations in 1997 with the opening of the Petronas Twin Towers in Kuala Lumpur, Malaysia. The record for world's tallest building remained in Asia with the opening of Taipei 101 in Taipei, Taiwan, in 2004. A number of architectural records, including that of the world's tallest building, will reside in the Middle East from 2009 with the opening of the Burj Dubai in Dubai, UAE.

This geographical transition is accompanied by a change in approach to skyscraper design. For much of the twentieth century large buildings such as the Willis Tower and World Trade Center (New York) took the form of simple geometrical shapes. This reflected the "international style" or modernist philosophy shaped by Bauhaus architects early in the century. By the 1990s skyscraper design began to exhibit postmodernist influences. The newest record setters, though modern, incorporate traditional architectural features associated with the part of the world where they stand. Design of Petronas Twin Towers is based on the transformation of simple but elegant Islamic geometric principles, Taipei 101 recalls the traditions of Asian pagoda architecture even as the Burj Dubai incorporates motifs from traditional Arabic art, reflecting the cultural influences of their environment.

For current rankings of skyscrapers by height, see List of tallest buildings in the world.

The following list measures height of the roof. The more common gauge is the highest architectural detail; such ranking would have included Petronas Towers, built in 1998. See List of tallest buildings in the world for details.