London is the capital (political) of England and the United Kingdom, the largest metropolitan area in the United Kingdom and the largest urban zone in the European Union by most measures. London has been a major settlement for two millennia, History of London going back to its founding by the Roman Empire, who called it ''Roman London''. London's ancient core, the City of London, largely retains its square-mile mediaeval boundaries. Since at least the 19th century, the name London has also referred to the metropolis developed around this core. The bulk of this conurbation forms the London Regions of England and the Greater London administrative area,See also: Independent cityNational capitals. governed by the elected Mayor of London and the London Assembly.
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. It is the world's largest financial centre alongside New York City, has the List of cities by GDP in Europe and is home to the headquarters of more than 100 of Europe's 500 largest companies. It is the most visited city in the world. London's five international airports make its airspace the busiest of any urban centre worldwide and London Heathrow Airport is the World's busiest airports by international passenger traffic. London's 43 universities form the largest concentration of higher education institutions in Europe. In 2012 London will become the first city to host the Summer Olympics three times.
London has a diverse range of peoples, cultures and religions, and more than 300 languages are spoken within its boundaries. In July 2007 it had an official population of 7,556,900 within the boundaries of Greater London, making it the Largest cities of the European Union by population within city limits. The Greater London Urban Area is the Largest urban areas of the European Union with a population of 8,278,251, while London's metropolitan area is the largest in the EU with an estimated total population of between 12 million and 14 million.
London contains four World Heritage Sites: the Tower of London; Royal Botanic Gardens, Kew; the site comprising the Palace of Westminster, Westminster Abbey and St. Margaret's, Westminster; and the historic settlement of Greenwich (in which the Royal Observatory, Greenwich marks the Greenwich Meridian (0° longitude) and GMT). Other famous landmarks include Buckingham Palace, the London Eye, Piccadilly Circus, 30 St Mary Axe, St Paul's Cathedral, Tower Bridge and Trafalgar Square. London is home to numerous museums, galleries, libraries, sporting events and other cultural institutions including the British Museum, National Gallery, British Library, The Championships, Wimbledon and 40 theatres. London's Chinatown, London is the largest in Europe. The London Underground network is the oldest underground railway network in the world and the most extensive after the Shanghai Metro.