London, United Kingdom

Greater London is one of nine regions of England and the top subdivision covering most of the metropolis. The City of London at its core once comprised the whole settlement; as its urban area grew, the Corporation of London resisted attempts to amalgamate the city with its suburbs, causing "London" to be defined several ways.

Forty per cent of Greater London is covered by the London post town, in which "London" forms part of postal addresses. The London telephone area code (020) covers an area similar in size to Greater London, although some outer districts are excluded and some just outside included. The London linked-number area extends 18 miles around Kings Cross, see Director telephone system. The Greater London boundary has been aligned to the M25 motorway in places.

Urban expansion is prevented by the Metropolitan Green Belt, although the built-up area extends beyond the boundary in places, producing a separately defined Greater London Urban Area. Beyond this is the London commuter belt. Greater London is split for some purposes into Inner London and Outer London, and by the River Thames into North and South, with an informal Central London area. The coordinates of the nominal "centre of London", traditionally the original Eleanor Cross at Charing Cross near the junction of Trafalgar Square and Whitehall, are about 51°30′26″N 00°07′39″W.

London's gross regional product in 2023 was £617.92 billion (US$846.46 billion) or around a quarter of UK GDP. London has five major business districts: the City, Westminster, Canary Wharf, Camden & Islington, and Lambeth & Southwark. Greater London had 27 million m2 of office space in 2001, and the City contains the most space, with 8 million m2 of office space. London has some of the highest real estate prices in the world.

London's finance industry is based in the City of London and Canary Wharf, the two major business districts. London took over as a major financial centre shortly after 1795 when the Dutch Republic collapsed before the Napoleonic armies. This caused many bankers established in Amsterdam to move to London. London's market-centred system grew more dominant in the 18th century. This economic strength of the city was attributed to its diversity. By the mid-19th century, London was the leading global financial centre; at the end of the century, over half the world's trade was financed in British currency. As of 2023, London ranks second in the world rankings on the Global Financial Centres Index and ranked second in A.T. Kearney's 2018 Global Cities Index.

According to a 2003 report, London has a quarter of the UK's leisure economy. The city is one of the four fashion capitals of the world, is the world's third-busiest film production centre, presents more live comedy than any other city, and has the biggest theatre audience of any city in the world. Alongside New York, London has been described as the cultural capital of the world.

The entertainment district of the West End has its focus around Leicester Square for film premieres, and Piccadilly Circus, with its giant electronic advertisements. It contains London's theatre district and Chinatown district. Agatha Christie's The Mousetrap, the world's longest-running play, has performed in the West End since 1952. Opera and ballet are performed at the Royal Opera House, the London Coliseum, Sadler's Wells Theatre and the Royal Albert Hall. London was the centre of music halls such as the Hackney Empire.

Islington's 1 mile (1.6 km) long Upper Street has more bars and restaurants than any other British street. Europe's busiest shopping area and England's longest shopping street is Oxford Street, nearly 1 mile (1.6 km) long. One of the world's largest retail destinations, London ranks near the top of retail sales of any city. In 2017, London was ranked the top city for luxury store openings. London Fashion Week takes place in February and September.

London is a major global centre of higher education, teaching and research and has the largest concentration of higher education institutes in Europe. According to the QS World University Rankings 2015/16, London has the greatest concentration of top class universities in the world and its international student population of around 110,000 is larger than any other city in the world. In the 2022 QS World University Rankings, Imperial College London is ranked No. 6 in the world, University College London (UCL) is ranked 8th, and King's College London (KCL) is ranked 37th. All are regularly ranked highly, with Imperial College being the UK's leading university in the Research Excellence Framework ranking 2021. The London School of Economics has been described as the world's leading social science institution for both teaching and research. The London Business School is one of the world's leading business schools. The city is home to three of the world's top ten performing arts schools (as ranked by the 2020 QS World University Rankings): the Royal College of Music (ranking 2nd in the world), the Royal Academy of Music (ranking 4th) and the Guildhall School of Music and Drama (ranking 6th).