A skyscraper is an extremely tall building. There is no minimum height for buildings to qualify as one, but they noticeably stand out in a city's skyline. The term originates from the name given to the tall sails on sailboats. Skyscrapers are typically made from a steel structure around a core column, which is usually formed from reinforced concrete that is made with cement blended with iron. This strong core contains the plumbing and elevators.
The tallest skyscrapers in the world include the Burj Khalifa in Dubai, United Arab Emirates; the Taipei 101 building in Taipei, Taiwan; the Petronas 1 and 2 in Kuala Lumpur, Malaysia; and the Willis Tower (better known as the Sears Tower) in Chicago. Burj Khalifa, opened in 2010, stands 2,722 feet (829.8 m) tall and has 163 floors. The Taipei 101 was built in 2004, has 101 floors and is 1,667 feet (508 m) tall. The Petronas Towers were constructed in 1998 and are each 88 stories with heights of 1,483 feet (452 m). Willis Tower was built in 1974, has 110 floors and is 1,451 feet (442 m) high. New York City's World Trade Center twin towers, built in 1972 and 1973 and destroyed 11 September 2001, were also 110 floors each, but were not as tall as the Willis Tower.
New York City is home to the world's oldest, and some of its tallest, skyscrapers. Two New York structures, The Trump Building and the Chrysler Building, are older than the world famous Empire State Building, but not as tall. The Empire State Building was built in 1931 with 102 stories and a height of 1,250 feet (381 m). The Chrysler Building, constructed in 1930, has 77 stories and is 1,046 feet (319 m) tall, while the Trump Building, also built in 1930, has 71 floors with a height of 927 feet (283 m). New York also has two more of the world's oldest and tallest buildings: The American International Building finished in 1932 at 67 stories and 952 feet (290m) and the G.E. Building, built in 1933 with 70 stories and a height of 850 feet (259 m).
Asia and the United States have the most skyscrapers. Hong Kong, Shanghai, and Dubai have many, while New York and Chicago contain the most in the US. Shanghai has at least four of the world's tallest buildings while Melbourne, Australia, and Toronto, Canada, have at least three. Atlanta and Houston are American cities that have at least three.