London i/ˈlʌndən/ 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 named it Londinium. London's ancient core, the City of London, largely retains its square-mile mediaeval 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 leading financial centre alongside New York City and has the fifth-largest city GDP in the world (and the largest in Europe). London has been described as a world cultural capital. It was the world's most visited city during 2011 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 in Europe. In 2012 London will become the first city to host the modern Summer Olympic Games three times.
Greater London is the top-level administrative division of England covering London. It was created in 1965 and spans the City of London and the 32 London boroughs. This territory has the same boundaries as the London Government Office Region and the London European Parliament constituency. The region has by far the highest GVA per capita in the United Kingdom. It covers 1,572 km2 (607 sq mi) and had a 2009 mid-year estimated population of 7,753,600. The term Greater London was in use before 1965 to refer to a variously defined area, larger than the County of London and often similar to the Metropolitan Police District.
In addition to its administrative and statistical functions, Greater London (excluding the City of London) is one of the 48 ceremonial counties of England, and is under the Greater London Lieutenancy.
Instead of forming a single political unit, London is divided into the small, interior City of London and the much wider Greater London. This arrangement has come about because as the area of London grew and absorbed neighbouring settlements, a series of administrative reforms did not fully amalgamate the City of London with the metropolitan area, and its unique political structure was retained. Outside the limited boundaries of the old city, a variety of arrangements governed the wider area since 1855, culminating with the creation of the Greater London administrative area in 1965.