London - city, capital of the United Kingdom and the centre of the Commonwealth. It lies astride the River Thames in southeastern England, 50 miles (80 km) from the river's estuary on the North Sea. The city was once the industrial, commercial, and political hub of a wealthy and extensive empire; it continues to be the United Kingdom's main centre of population, commerce, and culture.

A brief treatment of London follows. For full treatment (including a map), see London.

The chalk basin within which London is built is filled with younger sediments including solid rock, sands, clays, terraced pebble gravels, and Thames alluvium. The climate within the basin is relatively mild, with January to July mean temperatures ranging from 37.4 to 72.5 F (3 to 22.5 C); rainfall amounts to 21 inches (533 mm) a year.

Founded by the Romans as Londinium in the 1st century AD, the town experienced tremendous growth in trade and population during the late 16th and early 17th centuries. Extensive building projects were initiated after the Great Fire of 1666, and London became the dominant centre not only of the nation but of its expanding empire. During the 19th century, the problems caused by rapid industrialization, such as pollution and disease, were slowly remedied through advances in public health and other services. Heavy damage from aerial bombings during World War II brought the greatest setback in the history of modern London. Reconstruction and new development restored much of the city's grandeur, and relocation of manufacturing and shipping outside the city shrank its population and hastened its transition to a centre of international trade and finance. Tourism and retail trade are other major sectors of the city's economy; and, because London is the nation's capital, government services are also an important sector.

The City of London, about 1 square mile (2.7 square km) in area, is the core of an area called Inner, or Central, London, which contains the City of London and 13 of the 33 boroughs of Greater London. The central point in the City of London is an open space from which eight streets radiate. On the southern side is Mansion House, residence of the lord mayor of London. Lombard Street, the traditional banking street, is nearby, as are the Bank of England headquarters, the Royal Exchange, and the Stock Exchange. To the east is the fortress-castle known as the Tower of London, whose core dates from the late 11th century and is surrounded by constructions from many periods of English architecture. To the west lie the Inns of Court, longtime chambers and offices of barristers and lawyers-in-training, and the Royal Courts of Justice, or Law Courts. The City of London and the City of Westminster are linked by the Strand, an avenue upon which are located two of London's oldest churches, St. Clement Dane's and St. Mary-le-Strand.

The City of Westminster, which stretches along the River Thames, is one of the country's wealthiest boroughs and is famed for its commitment to historic renovation. It includes Westminster Abbey and Westminster Cathedral, Buckingham Palace, the principal government offices, important shopping districts, New Scotland Yard, luxury hotels, the Tate Gallery, and the National Gallery. Retail shopping areas are concentrated around Oxford Street. Kensington High Street and Knightsbridge are also major shopping districts. The shops spread west and south toward King's Road in Chelsea.

London's East End, containing neighbourhoods such as Aldgate and Whitechapel, now constitutes the borough of Tower Hamlets. The area is historically associated with the Cockney dialect and became an infamous slum during the 19th century. The East End was the most heavily bombed area of London during World War II and subsequently benefited from extensive rehabilitation.

Parks, gardens, and churchyards abound in Inner London. The most celebrated parklands are the six royal parks that sweep through London's West End: St. James's Park, oldest of the six central royal parks, bordered on the north by the half-mile-long Mall that terminates at the Queen Victoria Memorial; Buckingham Palace Gardens, bordered on the east by the royal residence; Green Park, plainest of the royal parks but fringed on the east by lavish, once-private buildings; Hyde Park, with its famous Speakers' Corner for soapbox orators; the more elegant Kensington Gardens, with the Victorian Gothic Albert Memorial and an 80-acre (32-hectare) cultural centre; and Regent's Park, home of the Zoological Gardens and Regent's (Grand Union) Canal.

Squares and variously shaped commons are prominent features of London's landscape. Of note are Grosvenor Square, site of the F.D. Roosevelt Memorial, and Trafalgar Square, which features a statue of Lord Nelson, hero of the Battle of Trafalgar (1805); the National Gallery borders the square.

London's other major cultural institutions include the British Museum, which houses collections of antiquities, prints, and manuscripts and the national library; the Victoria and Albert Museum of decorative arts; and the music and arts complex located on the South Bank of the Thames, begun in 1951 for the Festival of Britain.

The development of the city's outlying areas was promoted by the opening of the world's first electric underground railway in 1890. Major roads and rail lines radiate in all directions. Dock activity and river traffic are controlled by the Port of London Authority. The London (Heathrow) International Airport is located in the western reaches of Greater London. Area City, 1 square mile (2.7 square km); Inner London, 124 square miles (321 square km); Greater London, 610 square miles (1,579 square km). Pop. (1992 est.) City, 3,900; Inner London, 2,632,100; Greater London, 6,904,600.