The term was first applied to buildings of steel framed construction of at least 10 stories in the late 19th century, a result of public amazement at the tall buildings being built in major cities like Chicago, New York City, Detroit, and St. Louis. 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" and a skyscraper as "a multi-story building whose architectural height is at least 100 meters." Louis 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. After an early competition between Chicago and New York City 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.
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." 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, designed by Daniel Hudson Burnham and 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. (The 1889 Tower Building, designed by Bradford Gilbert and considered by some to be New York's first skyscraper, may have been the first building to use a skeletal steel frame.) Subsequent buildings such as the Singer Building, the Metropolitan Life Tower were higher still. Construction of the 133- floor, 640m supertall Digital Media City Landmark Building in Digital Media City, Seoul, South Korea, started in 2009, which will be the second-tallest building in the world when it is completed in 2015, housing the world's tallest observatory and hotels. Construction of the 110- floor, 510m supertall in Busan Lotte World, Busan, South Korea, started in 2009, which will be the third tallest building world when it is completed in 2013. 1 World Trade Center is now under construction and is the tallest tower comprising the redevelopment of the site of the former World Trade Center following the attacks of September 11, 2001.
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