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 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, a region governed by the Mayor of London and the London Assembly.
London has a diverse range of people and cultures, and more than 300 languages are spoken in the region. Its estimated mid-2016 municipal population (corresponding to Greater London) was 8,787,892, the largest of any city in the European Union (as of 2017), and accounting for 13.4% of the UK population. London's urban area is the second most populous in the EU, after Paris, with 9,787,426 inhabitants at the 2011 census. The city's metropolitan area is the most populous in the EU with 13,879,757 inhabitants, while the Greater London Authority states the population of the city-region (covering a large part of the south east) as 22.7 million. London was the world's most populous city from around 1831 to 1925.
Information from:
en.wikipedia.org/wiki/London 