London is the capital and most populous city of England and the United Kingdom. Standing 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 1.12-square-mile (2.9 km2) medieval boundaries and in 2011 had a resident population of 7,375, making it the smallest city in England. Since at least the 19th century, the term London has also referred to the metropolis developed around this core. 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. London has a diverse range of peoples and cultures, and more than 300 languages are spoken within Greater London. The Greater London Authority estimated its population to be 8.63 million in 2015, the largest of any municipality in the European Union. London's urban area is the second most populous in the EU, after Paris, with 9,787,426 inhabitants according to the 2011 census. The city's metropolitan area is one of the most populous in Europe with 13,879,757 inhabitants, while the Greater London Authority states the population of the city-region (covering a large part of south east England) as 22.7 million. London was the world's most populous city from around 1831 to 1925. London contains four World Heritage Sites: the Tower of London; Kew Gardens; the site comprising the Palace of Westminster, 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, Tate Modern, British Library and 40 West End theatres. The London Underground is the oldest underground railway network in the world. British Airways http://www.britishairways.com Golden Tours http://www.goldentours.com https://www.youtube.com/user/GoldenToursLondon City Cruises http://www.citycruises.com