London Underground

The London Underground was opened in 1863 and is the world's oldest. Sometimes called the tube, it is made up of 12 lines with 408km of track, much of which is underground. Although it's called the London Underground, almost half is above ground.

There are 275 stations. The fare system is fully automated with automatic checking on entry and exit at most stations and random inspections on trains. There is a penalty fare. The system serves just under a billion people yearly. During peak hours in the central area trains run every two and a half minutes.

The system serves Heathrow Airport.