London’s Underground, which opened in 1863, is not only the oldest subway system in the world, but the longest as well, with 244 miles of track.
Despite the name, about 55% of the subway network is above ground.
More than one billion passenger journeys were recorded in 2007, and the tube map, with its schematic and colour-coded layout, is considered a design classic.
The busiest station in the London Underground network is Victoria station, which serves about 78 million passengers a year.
For route maps and more history and facts about London’s subway, see http://www.tfl.gov.uk