London is the capital city of England and the United Kingdom, the largest metropolitan area in the United Kingdom, and the largest urban zone in the European Union by most measures. Located on the River Thames, London has been a major settlement for two millennia, its history going back to its founding by the Romans, who called it Londinium. London's ancient core, the City of London, largely retains its square-mile medieval boundaries. Since at least the 19th century, the name London has also referred to the metropolis developed around this core. The bulk of this conurbation forms the London region and the Greater London administrative area, governed by the elected Mayor of London and the London Assembly.
London is a leading global city, with strengths in the arts, commerce, education, entertainment, fashion, finance, healthcare, media, professional services, research and development, tourism and transport all contributing to its prominence. It is the world's largest financial centre alongside New York City and has the largest city GDP in Europe. It has the most international visitors of any city in the world and London Heathrow is the world's busiest airport by number of international passengers. London's 43 universities form the largest concentration of higher education institutions in Europe. In 2012 London will become the first city to host the modern Summer Olympic Games three times.