London Underground stations that are listed buildings London Underground stations that are listed buildings The London Underground is a metro system serving a large part of Greater London and parts of Buckinghamshire, Hertfordshire and Essex. Seventy-one of the 270 London Underground stations use buildings that are on the Statutory List of Buildings of Special Architectural or Historic Interest, and five have entrances in listed buildings. Buildings are given one of three grades: Grade I for buildings of exceptional interest, Grade II* for particularly important buildings of more than special interest and Grade II for buildings that are of special interest. The Metropolitan Railway's original seven stations were
London Underground infrastructure London Underground infrastructure The infrastructure of the London Underground includes 11 lines, with 270 stations. There are two types of line on the London Underground: services that run on the sub-surface network that is just below the surface and use larger trains, and the deep-tube lines, that are for the most part self-contained and use smaller trains. Most of the lines emerge on to the surface outside the central area. The oldest trains running on the Underground were introduced in 1972. The Underground is electrified using a four-rail system, the DC traction supply being independent of the running rails. Planned