Geograph - photograph every grid square

Mark Wallinger, one of the UK’s leading contemporary artists, has created a major new artwork for London Underground to celebrate its 150th anniversary. The result, commissioned by Art on the Underground, is a multi-part work on a huge scale that will be installed in every one of the Tube’s 270 stations.

Southgate is a London Underground Piccadilly line station in Southgate. It is located between Arnos Grove and Oakwood stations and is in Travelcard Zone 4. The station opened in 1933. The station is built in the Art Deco/Streamline Moderne design style using brick, reinforced concrete and glass and is one of the best known of the many stations Charles Holden designed for London Underground. The station building is circular with a flat projecting concrete roof.
Grade II* listed. Link
Link

The London Underground system is also known as the "Tube". It is the oldest underground system in the world, the first section dating from 1863. The present system has over 250 miles of track and 272 stations. There are 11 lines covering Greater London, Essex, Buckinghamshire & Hertfordshire. Nearly half the system is above ground.
Wikipedia: Link
Transport for London: Link

A few years ago I read a book by Mark Mason "Walking the lines" in which he walked the route of the London Underground lines, overground. I will repeat this visiting all 272 stations (some more than once). My route tries to follow the line of the railway as closely as possible, using footpaths and roads, deviations are made to make the walk more "interesting".