Community action/London

London is the capital and largest city of both England and the United Kingdom, with a population of 9.1 million people in 2024. Its wider metropolitan area is the largest in Western Europe, with a population of 15.1 million. London stands on the River Thames in southeast England, at the head of a 50-mile (80 km) tidal estuary down to the North Sea, and has been a major settlement for nearly 2,000 years. Its ancient core and financial centre, the City of London, was founded by the Romans as Londinium and has retained its medieval boundaries. The City of Westminster, to the west of the City of London, for centuries has been as the site of the national government and parliament. London grew rapidly in the 19th century, becoming the world's largest city at the time. Since the 19th century the name "London" has referred to the metropolis around the City of London, historically split among the counties of Middlesex, Essex, Surrey, Kent and Hertfordshire. Since 1965 it has largely comprised the administrative area of Greater London, governed by 33 local authorities and the Greater London Authority.

As one of the world's major global cities, London exerts a strong influence on world art, entertainment, fashion, commerce, finance, education, healthcare, media, science, technology, tourism, transport and communications. London is Europe's largest city economy and one of the world's major financial centres. London hosts Europe's largest concentration of higher education institutions, comprising over 50 universities and colleges and enrolling more than 500,000 students in 2023. It is home to several of the world's leading academic institutions; Imperial College London, internationally recognised for its excellence in natural and applied sciences, and University College London (UCL), a comprehensive research-intensive university, consistently rank among the top ten globally. Other notable institutions include King's College London (KCL), highly regarded in law, humanities and health sciences; the London School of Economics (LSE), globally prominent in social sciences and economics; and specialised institutions such as the Royal College of Art (RCA), Royal Academy of Music (RAM), the Royal Academy of Dramatic Art (RADA), the School of Oriental and African Studies (SOAS) and London Business School (LBS). It is the most-visited city in Europe and has the world's busiest city airport system. The London Underground is the world's oldest rapid transit system.

London's diverse cultures encompass over 300 languages. The 2025 population of Greater London of just over 9.8 million made it Europe's third-most populous city, accounting for 13.1 per cent of the United Kingdom's population and 15.5 per cent of England's population. The Greater London Built-up Area is the fourth-most populous in Europe, with about 9.8 million inhabitants as of 2011. The London metropolitan area is the third-most-populous in Europe, with about 15 million inhabitants as of 2025, making London a megacity.