The world's oldest underground train system is the London Underground, known to most as the 'Tube'.
Services began in 1863 on the Metropolitan line which ran between
Paddington and Farringdon stations.
There are now 12 different tube lines serving 204 different stations
running over 253 miles of track.
As the London Underground is so historic, the need for certain
destinations on the map has changed over the years, resulting in a number of
stations becoming disused. Aldwych Underground station on the Strand, is
probably the most famous of these 'ghost' stations. It closed down
in 1994 and is still visible at street level.
Another problem associated with the age of the Tube, is the heat. The
air in the stations can become stifling during the summer, but
unfortunately because the Tube was invented long before air-conditioning was
available, no provision was made for its installation.
The future of the Tube looks bright though, with plans afoot to extend the
East London line down from New Cross Gate to Crystal Palace in 2010.

 The London Underground (also referred to as the Tube) is the world's oldest underground train system. The Underground dates back to 1863 and was then called the Metropolitan Railway. Trains ran at 10 minute intervals and over 40,000 passengers used the train line on its first day of operation.

The original purpose of the Underground was to serve as an inexpensive and efficient service for the working-class, in order to allow them to commute between the central and industrial areas of London and outer country districts.

The mid-19th century was a time of great fascination with trains and railway lines in Great Britain and much of Europe. The widespread popular interest in this form of transport provided the much need impetus for costly projects, such as the construction of London's Metropolitan Railway.