Passengers on the London Underground had the chance to see a rare sight when a steam train made its way along the Metropolitan line.
The old-fashioned train carried lucky passengers as part of celebrations to mark the 150th anniversary of the Tube, which opened on January 8, 1863.
London Mayor Boris Johnson was among those lucky enough to have a ticket for the special journey.
"It's a beautiful, beautiful way of getting around. It's inspired imitators around the planet and there is no other system as good as London Underground," Mr Johnson said.
The Metropolitan Railway was the world's first underground rail network, and stretched less than four miles between Paddington and Farringdon.
On its opening day, 40,000 commuters jumped on board the steam powered locomotives.
Since then, the Tube has become more than just a way of getting from A to B.
Its long history, and the vital role it continues to play in Londoners' lives, means the Tube is now as famous as the city it serves.
During its 150 years, the Underground has matured alongside the people of London, witnessing and sharing the trials and tribulations of its passengers.
During the Blitz, almost 200,000 people regularly used its tunnels to shelter from the aerial bombardment.
A series of events has been planned for 2013 to commemorate the Tube's birthday.
As well as heritage rail trips, the Royal Mail will be issuing a set of stamps to celebrate the history of the Underground, and the Royal Mint will be commissioning two new two-pound coins.