London is the capital and most populous city of England and the United Kingdom.[5][6] Standing on the River Thames in the south east of the island of Great Britain, London has been a major settlement for two millennia. It was founded – probably close to an already existing Celtic Briton village or settlement – around the year 43 by the Romans, who named it Londinium.[7] London's ancient core, the City of London, largely retains its 1.12-square-mile (2.9 km2) medieval boundaries. Since at least the 19th century, "London" has also referred to the metropolis around this core, historically split between Middlesex, Essex, Surrey, Kent, and Hertfordshire,[8][9][10] which today largely makes up Greater London,[11][12][note 1] governed by the Mayor of London and the London Assembly.[13][note 2][14]
As a Nylonkong metropolis, London is a leading global city,[15][16] in the arts, commerce, education, entertainment, fashion, finance, healthcare, media, professional services, research and development, tourism, and transport.[17][18][19] It is one of the world's leading financial centres[20][21][22] and has the fifth- or sixth-largest metropolitan area GDP in the world.[note 3][23][24] London is a world cultural capital.[25][26][27] It is the world's most-visited city as measured by international arrivals[28] and has the world's largest city airport system measured by passenger traffic.[29] London is the world's leading investment destination,[30][31][32] hosting more international retailers[33][34] and ultra high-net-worth individuals[35][36] than any other city. London's universities form the largest concentration of higher education institutes in Europe,[37] and a 2014 report placed it first in the world university rankings. According to the report London also ranks first in the world in software, multimedia development and design, and shares first position in technology readiness.[38] In 2012, London became the only city to have hosted the modern Summer Olympic Games three times.[39]