London is the capital and largest city of England and the United Kingdom. Standing on the River Thames in the south-east of England, London has been a major settlement for two millennia. Londinium was founded by the Romans.
London is considered to be one of the world's most important global cities. It is the most-visited city as measured by international arrivals and has the busiest city airport system as measured by passenger traffic. It is the leading investment destination, hosting more international retailers than any other city.
London is the seat of the Government of the United Kingdom. Many government departments, as well as the Prime Minister's residence at 10 Downing Street, are based close to the Palace of Westminster, particularly along Whitehall. The British Parliament is often referred to as the "Mother of Parliaments", because it has been a model for many other parliaments.
London encompasses a total area bigger than 1,500 km^2 and has a population of more than 9 million of inhabitants. The 37% of London's population is foreign-born, making London the city with the second largest immigrant population, behind New York City. The 69% of children born in London has at least one parent who is born abroad.
With increasing industrialisation, London's population grew rapidly throughout the 19th and early 20th centuries, and it was for some time in the late 19th and early 20th centuries the most populous city in the world.