The Tube handles up to 4 million passenger journeys per day. At peak times there are more than 535 trains whizzing around the Capital.
More people than ever are using the Tube, with more trains running than at any time in its history.
However, some of the equipment being relied on is decades old - including a signal box from 1926 still in use at Edgware Road.
For the Tube to continue working smoothly, continued improvements are essential.
We are carrying out a multi-billion pound programme to increase capacity and accessibility and to run services more reliably and more frequently.
It includes introducing new trains, signalling and track, and rebuilding some of the busiest and most complex stations.
Projects already completed include:
We are responsible for all aspects of the Tube's operations including running the trains, stations and control centres, making sure the Tube is safe and secure, and collecting and protecting fares revenue.
We are also responsible for the maintenance and renewal of most of the infrastructure used by the Tube, although some services run over track that is the responsibility of Network Rail.