The London Underground is the oldest transport system in the world, opening in 1863.
The system is currently going through a multi-million capacity improvement programme, which will see massive benefits for passengers for years to come.
Several stations have been made step-free and many station enlargement programmes are in progress.
The system has one of the most famous catch phrases - Mind the Gap!
Transport for London Oystercards and Travelcards are valid on the London Underground network.