London is the capital city of the United Kingdom.
Standing on the River Thames in southeastern England, upstream from its estuary with the North Sea, London has been a major settlement for two millennia. Londinium was founded by the Romans. The City of London, London's ancient core − an area of just and colloquially known as the Square Mile − retains its medieval boundaries. [See also: Independent city § National capitals.] The City of Westminster is also an Inner London borough holding city status. Greater London is governed by the Mayor of London and the London Assembly. [The London Mayor is not to be confused with the Lord Mayor of London who heads the City of London Corporation, which administers the City of London.] [Lieutenancies Act 1997]
London is a leading global city in the arts, commerce, education, entertainment, fashion, finance, healthcare, media, professional services, research and development, tourism and transportation. London, the fourth fastest-growing city, is 26 out of 300 major cities for economic performance. [https://money.cnn.com/2015/01/22/news/economy/london-fastest-growing-western-city/index.html] It is one of the largest financial centres [ Accessed 7 October 2018.] and has either the fifth or sixth largest metropolitan area GDP. [Rankings of cities by metropolitan area GDP can vary as a result of differences in the definition of the boundaries and population sizes of the areas compared, exchange rate fluctuations and the method used to calculate output. London and Paris are of broadly similar size in terms of total economic output which can result in third party sources varying as to which is the fifth-largest city GDP in the world. A report by the McKinsey Global Institute published in 2012 estimated that London had a city GDP of US$751.8 billion in 2010, compared to US$764.2 billion for Paris, making them respectively the sixth- and fifth-largest in the world. A report by PricewaterhouseCoopers published in November 2009 estimated that London had a city GDP measured in purchasing power parity of US$565 billion in 2008, compared to US$564 billion for Paris, making them respectively the fifth- and sixth-largest in the world. The McKinsey Global Institute study used a metropolitan area with a population of 14.9 million for London compared to 11.8 million for Paris, whilst the PricewaterhouseCoopers study used a metropolitan area with a population of 8.59 million for London compared to 9.92 million for Paris.] It is the most-visited city as measured by international arrivals and has the busiest city airport system as measured by passenger traffic. It is the leading investment destination, hosting more international retailers and ultra high-net-worth individuals than any other city. London's universities form the largest concentration of higher education institutes in Europe. In 2012, London became the first city to have hosted three modern Summer Olympic Games.
London has a diverse range of people and cultures, and more than 300 languages are spoken in the region. Its estimated mid-2016 municipal population was 8,787,892, the most populous of any city in the European Union [ name="largest_city_eu">] and accounting for 13.4% of the UK population. London's urban area is the second most populous in the EU, after Paris, with 9,787,426 inhabitants at the 2011 census. The population within the London commuter belt is the most populous in the EU with 14,040,163 inhabitants in 2016. London was the world’s most populous city from 1831 to 1925.
London contains four World Heritage Sites: the Tower of London; Kew Gardens; the site comprising the Palace of Westminster, 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. 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. These include the British Museum, National Gallery, Natural History Museum, Tate Modern, British Library and West End theatres. The London Underground is the oldest underground railway network in the world.