London Underground, aka the Tube, marks its 150th birthday on Wednesday.
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 STG2 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.
Serving 270 stations, the Tube 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.
During the morning rush hour London's busiest Tube station is Waterloo, with 57,000 people entering during the three-hour peak. The busiest station in terms of passengers each year is also Waterloo with 82 million.
Today the Underground provides jobs for around 19,000 people.
Paying tribute, 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."
TfL said it would continue to make improvements to the services provided, with recent ones including a fleet of new air-conditioned trains which have been introduced on the Metropolitan line, and over the next few years will be rolled out to some two fifths of the Tube network.
Higher frequency services on the Victoria and Central lines are also promised for this year.
By the end of next year, the Northern line upgrade will be completed, with higher frequency services, and key stations in central London such as Victoria and Tottenham Court Road will have been rebuilt.
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.
On Sunday, the first Tube passenger journey will be recreated with a steam train travelling between Kensington Olympia and Moorgate Tube stations.
Mike Brown, managing director of London Underground, said: "As we mark the 150th anniversary of the world's first underground railway we are also building for the future - transforming stations and replacing trains, signals and track.
"This year will see even more - with a greater frequency of services on the Central and Victoria lines and more of the new air-conditioned trains, which will soon serve 40 per cent of the Tube network.
"It is this sustained investment that will enable us to create a network able to support London's growing population and maintain our city's vital role in the UK economy for the next 150 years."