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 lines share all their stations and most of the track with other lines. The Bakerloo, Central, Jubilee, Northern, Piccadilly, Victoria and Waterloo & City lines are deep-level tubes, with smaller trains that run in two circular tunnels with a diameter of about , lined with cast-iron or precast concrete rings, which were bored using a tunnelling shield. It is these that were the "tube" lines, although since the 1950s the term "tube" has come to be used to refer to the whole London Underground system. Many of the central London deep-tube line stations, such as those on the Central and