The London Underground is a metro system serving a large part of Greater London and neighbouring areas of Essex, Hertfordshire and Buckinghamshire in England. It is both the world's oldest underground railway and the oldest rapid transit system. It was also the first underground railway to operate electric trains. It is usually referred to as the Underground or the Tube - the latter deriving from the shape of the system's deep-bore tunnels - although about 55% of the network is above ground.

The earlier lines of the present London Underground network, which were built by various private companies, became part of an integrated transport system (which excluded the main line railways) in 1933 with the creation of the London Passenger Transport Board (LPTB), more commonly known by its shortened name: "London Transport". The underground network became a single entity when London Underground Limited (LUL) was formed by the UK government in 1985. Since 2003 LUL has been a wholly owned subsidiary of Transport for London (TfL), the statutory corporation responsible for most aspects of the transport system in Greater London, which is run by a board and a commissioner appointed by the Mayor of London.

The Underground has 268 stations and approximately 400 km (250 miles) of track,According to " ", the total route length is 253 mi or 408 km. However, in July 2007 the same page showed the same route length even though there were more stations. Thus it must not have been fully updated for the closure of the East London Line, whose route length was about 7 km. making it the longest metro system in the world by route length, and one of the most served in terms of stations. In 2007, over one billion passenger journeys were recorded.

History

main: History of the London Underground Railway construction in the United Kingdom began in the early 19th century. By 1854 six separate railway terminals had been built just outside the centre of London: London Bridge, Euston, Paddington, King's Cross, Bishopsgate and Waterloo. At this point, only Fenchurch Street Station was located in the actual City of London. Traffic congestion in the city and the surrounding areas had increased significantly in this period, partly due to the need for rail travellers to complete their journeys into the city centre by road. The idea of building an underground railway to link the City of London with the mainline terminals had first been proposed in the 1830s, but it was not until the 1850s that the idea was taken seriously as a solution to the traffic congestion problems. , at pp.3-4

The first underground railways

In 1854 an Act of Parliament was passed approving the construction of an underground railway between Paddington Station and Farringdon Street via King's Cross which was to be called the Metropolitan Railway. The Great Western Railway (GWR) gave financial backing to the project when it was agreed that a junction would be built linking the underground railway with their mainline terminus at Paddington. GWR also agreed to design special trains for the new subterranean railway.