London Underground

The London Underground is a system of trains running underneath London. In the 1970s the platforms and tunnels of the system were used by the Great Intelligence to pull in the Doctor and his companions Jamie McCrimmon and Victoria Waterfield in the TARDIS and have them attacked by its Robot Yetis. (DW: The Web of Fear)

Sarah Jane Smith once saved the Underground from a terrorist attack. (BFSJS: Test of Nerve)

The Doctor visited Aldgate underground station because it passed close to the chamber where the Water Hive were holding their prisoners. (TDA: The Feast of the Drowned)

There are parts of the Torchwood Hub which were built in a similar style to the old underground stations. (TW: Everything Changes onwards)

Behind the scenes
In 2007 BBC Three did a London Underground night in which they broadcast episode 1 of The Web of Fear.