Can you visit all 270 London Underground stations?
With this year marking the 150th anniversary of the London Underground public transport system, a number of special events and activities are being held to celebrate the world's oldest subterranean railway network.
Among these is a wonderful exhibition of retro poster art at the London Transport Museum, which can be found in Covent Garden.
However, anyone who wants to really get a feel for the iconic tube network may want to try and emulate Geoff Marshall and Anthony Smith, who recently broke the record for visiting all 270 stations in the quickest time.
The pair were aiming to beat the previous record of 16 hours, 29 minutes and 13 seconds set by Andy James and Steve Wilson in May 2011, and managed to shave a full eight minutes off this time to book secure their place in the Guinness World Records book.
Speaking after their achievement, Mr Marshall - who has now held this record twice after attempting the feat on no fewer than 25 occasions - expressed his love of the London Underground network, commenting: "It's like the wheels of a bicycle spoke - you start on the outside and then go back into London, everything comes into the middle."
Of course, visiting every single tube station on one visit to the capital may be a bit ambitious for most people, but a trip to a few of the most prominent ones is always exciting.
Many are steeped in history, having provided shelter for Londoners during the air raids of World War II while also playing a significant role in other key events over the past century and a half.
Both Farringdon and Covent Garden stations, for example, are said to be haunted by people murdered nearby, while the Metropolitan Line - which opened on January 10th 1863 - is the oldest tube line in the world.