London Underground has turned 150.
The first stretch of the world-famous network opened on January 9 1863, with the first passenger journeys taking place the following day.
London Underground is planning a series of events to celebrate the milestone year including a series of additional heritage rail trips using steam trains, two new two-pound coins and a set of 10 special stamps issued by Royal Mail.
The Mayor of London, Boris Johnson, described the network as "arguably the best, and most iconic, underground transport system in the world".
Since the first stretch of track was opened between Paddington and Farringdon, then known as the Metropolitan Railway, the network has expanded to 12 lines. Carrying 1,107 million passengers a year and serving 270 stations, it links central London to Surrey, Kent, Essex, Hertfordshire, Middlesex and Buckinghamshire.
The network carried record numbers of passengers in 2011/12, with 1.171 billion journeys made, according to Transport for London (TfL). This is 64 million more passenger journeys than the previous year, which itself had set a new record.
Paying tribute, Mr Johnson said: "The arrival of the Tube was truly revolutionary and today it is still admired around the world. It annihilates distance, liquidates traffic and is the throbbing cardiovascular system of the greatest city on earth. It continues to play a hugely important role in the success of our capital - efficiently moving record numbers of people during the London 2012 Games.
"Our massive upgrade programme builds on the engineering ingenuity of our Victorian forefathers and through new signalling, trains and track, millions of Londoners and visitors will continue to benefit from what is arguably the best, and most iconic, underground transport system in the world."
The 150th anniversary of the world's first underground railway will also be marked with the publication of a comprehensive new history of the Tube - Underground, How The Tube Shaped London - which is co-authored by Sam Mullins, the director of the London Transport Museum.
Twelve short stories by well-known authors, one about each Tube line, will also look at the meaning of the Underground for those who live in and visit the city. Other events include a poster art exhibition at London Transport Museum next month and a series of theatrical events at the disused Aldwych station.