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
M25 motorway are in Buckinghamshire, 17–25 are in Hertfordshire, and 26–31 are in Essex. Policing of the road is carried out by an integrated policing group made up of the Metropolitan, Thames Valley, Essex, Kent, Hertfordshire and Surrey forces. The M25 is one of Europe's busiest motorways. In 2003, a maximum of 196,000 vehicles a day were recorded on the motorway just south of London Heathrow Airport between junctions 13 and 14. The idea of an orbital road around London was first proposed early in the 20th century. An outer orbital road around London had first been proposed in 1913, and was