London is the capital and largest city of England and the United Kingdom.[7][8] It stands on the River Thames in south-east England at the head of a 50-mile (80 km) estuary leading to the North Sea. London has been a major settlement for two millennia.[9] The City of London, its ancient core and financial centre, was founded by the Romans as Londinium. Known colloquially as the Square Mile, it retains boundaries that closely follow its medieval limits.[note 1][10][11][12][13][14] The adjacent City of Westminster has for centuries housed the national government. London has 31 additional boroughs north and south of the river. The London region is governed by the mayor of London and the London Assembly.[note 2][15][16]

Willis Building
Clockwise from top: City of London in the foreground with Canary Wharf in the far background, Trafalgar Square, London Eye, Tower Bridge and a London Underground roundel in front of Elizabeth Tower
Location within the United Kingdom
Location within England
Location within Europe
London (Earth)
Coordinates: 51°30′26″N 0°7′39″W
Sovereign state United Kingdom
Country England
CountiesGreater London
City of London
Settled by RomansAD 47[1]
as Londinium
DistrictsCity of London and 32 boroughs
  TypeExecutive mayoralty and deliberative assembly within unitary constitutional monarchy
  BodyGreater London Authority
Mayor Sadiq Khan (L)
London Assembly
  London Assembly14 constituencies
  UK Parliament73 constituencies
  Total[upper-alpha 1]1,572 km2 (607 sq mi)
1,737.9 km2 (671.0 sq mi)
8,382 km2 (3,236 sq mi)
  City of London2.90 km2 (1.12 sq mi)
  Greater London1,569 km2 (606 sq mi)
Elevation11 m (36 ft)
  Total[upper-alpha 1]8,961,989[4]
  Density5,666/km2 (14,670/sq mi)
14,257,962[5] (1st)
  City of London
8,706 (67th)
  Greater London
GVA (2019)
  Total£503 billion
($642 billion)
  Per capita£56,199
Time zoneUTC (Greenwich Mean Time)
  Summer (DST)UTC+1 (British Summer Time)
Postcode areas
22 areas
Area codes
  • 020, 01322, 01689, 01708, 01737, 01895, 01923, 01959, 01992
International airportsHeathrow (LHR)
City (LCY)
Gatwick (LGW)
Stansted (STN)
Luton (LTN)
Southend (SEN)
Rapid transit systemUnderground
PoliceMetropolitan (excluding the City of London square-mile)

London is one of the world's major global cities.[17] It exerts strong influence on the arts, commerce, education, entertainment, fashion, finance, health care, media, professional services, research and development, tourism and transportation.[18] With a GDP of €801.66 billion in 2017, London is the biggest urban economy in Europe.[19] It is one of the largest financial centres in the world and in 2019 had the second highest number of ultra high-net-worth individuals in Europe after Paris.[20] In 2020 London had the second-highest number of billionaires of any city in Europe, after Moscow.[21] London's universities form Europe's largest concentration of higher education institutions.[22] Its high-ranking institutions include Imperial College London in natural and applied sciences, the London School of Economics in social sciences, and the comprehensive University College London.[23] In 2012, London became the first city to have hosted three modern Summer Olympic Games.[24]

London's diverse range of people and cultures mean that more than 300 languages are spoken.[25] Its mid-2018 population (corresponding to Greater London) was about 9 million,[3] which made it Europe's third-most populous city.[26] London accounts for 13.4% of the UK population.[27] Greater London Built-up Area is the fourth-most populous in Europe, after Istanbul, Moscow, and Paris, with 9,787,426 inhabitants at the 2011 census.[28][29] The London metropolitan area is the third-most populous in Europe, after Istanbul and the Moscow Metropolitan Area, with 14,040,163 inhabitants in 2016.[note 3][5][30]

London has four World Heritage Sites: the Tower of London; Kew Gardens; the Palace of Westminster along with Westminster Abbey, and St Margaret's Church; and the historic settlement in Greenwich, where the Royal Observatory, Greenwich defines the Prime Meridian (0° longitude) and Greenwich Mean Time.[31] Other landmarks include Buckingham Palace, the London Eye, Piccadilly Circus, St Paul's Cathedral, Tower Bridge, Trafalgar Square and The Shard. London has numerous museums, galleries, libraries and sporting events. They include the British Museum, National Gallery, Natural History Museum, Tate Modern, British Library and West End theatres.[32] The London Underground is the oldest rapid transit system in the world.