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, has been the centuries-long host 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 between the counties of Middlesex, Essex, Surrey, Kent and Hertfordshire, which since 1965 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 is 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 as at 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.

Four World Heritage Sites are located in London: Kew Gardens; the Tower of London; the site featuring the Palace of Westminster, the Church of St Margaret, and Westminster Abbey; and the historic settlement in Greenwich where the Royal Observatory defines the prime meridian (0° longitude) and Greenwich Mean Time. Other landmarks include Buckingham Palace, the London Eye, Piccadilly Circus, St Paul's Cathedral, Tower Bridge and Trafalgar Square. The city has the most museums, art galleries, libraries and cultural venues in the UK, including the British Museum, the National Gallery, the Natural History Museum, Tate Modern, the British Library and numerous West End theatres. Important sporting events held in London include the FA Cup Final, the Wimbledon Tennis Championships and the London Marathon. It became the first city to host three Summer Olympic Games upon hosting the 2012 Summer Olympics.

London is an ancient name, attested in the first century AD, usually in the Latinised form Londinium. Modern scientific analyses of the name must account for the origins of the different forms found in early sources: Latin (usually Londinium), Old English (usually Lunden), and Welsh (usually Llundein), with reference to the known developments over time of sounds in those different languages. It is agreed that the name came into these languages from Common Brythonic; recent work tends to reconstruct the lost Celtic form of the name as *Londonjon or something similar. This was then adapted into Latin as Londinium and borrowed into Old English.

Until 1889, the name "London" applied officially only to the City of London, but since then it has also referred to the County of London and to Greater London.

In 1993 remains of a Bronze Age bridge were found on the south River Thames foreshore, upstream from Vauxhall Bridge. Two of the timbers were radiocarbon dated to 1750–1285 BC. In 2010 foundations of a large timber structure, dated to 4800–4500 BC, were found on the Thames' south foreshore downstream from Vauxhall Bridge. Both structures are on the south bank of the Thames, where the now-underground River Effra flows into the Thames.

Despite the evidence of scattered Brythonic settlements in the area, the first major settlement was founded by the Romans around AD 47, about 4 years after their invasion of AD 43. This only lasted until about AD 61, when the Iceni tribe led by Queen Boudica stormed it and burnt it to the ground.