London, the capital and largest city of the United Kingdom, has 128 completed buildings that are at least 100 metres (328 feet) tall as of 2025, 42 of which have a height greater than 150 metres (492 ft). London has one of the largest skylines in Europe; it has the most skyscrapers taller than 150 m (492 ft) in the United Kingdom and in Western Europe, and the third most of any city in Europe overall, after Moscow and Istanbul. London's skyline has undergone immense transformation in the early 21st century. Since 2013, the tallest building in London and the United Kingdom has been The Shard, the only supertall skyscraper. The pyramid-shaped building in Southwark rises to a height of 306 m (1,004 ft). London has two primary skyscraper clusters: the City of London in central London, and Canary Wharf with the Isle of Dogs in East London, alongside numerous smaller groupings throughout Greater London.
For two centuries since 1710, St Paul's Cathedral was the tallest structure in London. While early skyscrapers sprouted in the late 19th and early 20th century in the United States, London—then the world's largest city—avoided this trend. In 1894, after work on the 12-storey Queen Anne’s Mansions, the London Building Act imposed a height limit of 30 m (98 ft) or less across the city. This restriction was lifted in the 1950s, permitting the construction of high-rises taller than St. Paul's. The destruction during The Blitz allowed more room for modern development. Early skyscrapers were built on the west side of central London, most notably the BT Tower in Fitzrovia in 1965. A concentration of tall buildings arose in the City of London, including office towers such as St Helen's and Tower 42, and Barbican Estate, a three-towered residential complex that is a prominent example of brutalism. The London Docklands in the Isle of Dogs, which had become disused in the 1960s, underwent a significant redevelopment plan in the 1980s, resulting in the financial district of Canary Wharf. Among the first skyscrapers built there was One Canada Square in 1991. At 236 m (774 ft), it surpassed Tower 42 to be London's tallest building; it is currently the city's third-tallest building and still the tallest in Canary Wharf.