London is the capital and largest city of England and the United Kingdom. Located in southeast England on the River Thames, it sits at the head of a 50-mile tidal estuary that leads to the North Sea. As of 2024, the city has a population of 9.1 million people, while its wider metropolitan area is the largest in Western Europe with a population of 15.4 million.
The city has served as a major settlement for nearly 2,000 years. Its ancient core and financial center, known as the City of London, was originally founded by the Romans as Londinium and maintains its medieval boundaries. To the west lies the City of Westminster, which has hosted the national government and parliament for centuries. While it grew rapidly in the 19th century to become the world's largest city at that time, the modern metropolis is largely comprised of the administrative area of Greater London.