London is the capital and most populous city of England and the United Kingdom. Standing on the River Thames in the south east of the island of Great Britain, London has been a major settlement for two millennia. It was founded by the Romans, who named it Londinium. London's ancient core, the City of London, largely retains its 1.12-square-mile (2.9 km2) medieval boundaries. Since at least the 19th century, "London" has also referred to the metropolis around this core, historically split between Middlesex, Essex, Surrey, Kent, and Hertfordshire, which today largely makes up Greater London, governed by the Mayor of London and the London Assembly.
London contains four World Heritage Sites: the Tower of London; Kew Gardens; the site comprising the Palace of Westminster (image below), Westminster Abbey, and St Margaret's Church; and the historic settlement of Greenwich (in which the Royal Observatory, Greenwich marks the Prime Meridian, 0° longitude, and GMT). Other famous landmarks include Buckingham Palace, the London Eye, Piccadilly Circus, St Paul's Cathedral, Tower Bridge, Trafalgar Square, and The Shard. London is home to numerous museums, galleries, libraries, sporting events, and other cultural institutions, including the British Museum, National Gallery, Natural History Museum, Tate Modern, British Library, and West End theatres. The London Underground is the oldest underground railway network in the world.
This post is part of the Travel Tuesday meme.