London Underground

London Underground
Info
Locale	Greater London, Chiltern, Epping Forest, Three Rivers and Watford
Transit type	Rapid transit
Number of lines	11
Number of stations	270 served (260 owned)
Daily ridership	about 3.23 million
Website	www.tfl.gov.uk/tube
Operation
Began operation	10 January 1863
Operator(s)	London Underground Ltd; part of Transport for London (TfL)
Technical
System length	402 kilometres (250 mi)
Track gauge	1,435 mm (4 ft 8 1⁄2 in) standard gauge

The London Underground is a form of public transport in London. It is a rapid transit system that uses electric trains. It is the oldest underground railway in the world. It started running in 1863 as the Metropolitan Railway. After the opening the system was copied in many other cities, for example New York and Madrid. Even though it is called the Underground about half of it is above the ground. The "Tube" is a slang name for the London Underground, because the tunnels for some of the lines are round tubes running through the ground. The Underground serves 272 stations and over 408 km of track. From 2006 to 2007 over 1 billion passengers used the underground.

Underground train systems in other cities may be called metros (like the Tyne and Wear Metro in North East England) or subways (Glasgow Subway in Scotland and in most of North America). Subway is also used across Britain to refer to underground walkways.