London Underground Buses, Tramlink, London Overground, London River Services and Docklands Light Railway. Crossrail, due to open in 2019, is to be identified with a roundel. The 100th anniversary of the roundel was celebrated in 2008 by TfL commissioning 100 artists to produce works that celebrate the design. Seventy 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. The Metropolitan Railway's original seven stations were inspired by Italianate designs, with the platforms lit by daylight from above and by gas lights in
London to amalgamate the city with its suburbs, causing "London" to be defined in a number of ways for different purposes. Forty per cent of Greater London is covered by the London post town, within which 'LONDON' forms part of postal addresses. The London telephone area code (020) covers a larger area, similar in size to Greater London, although some outer districts are excluded and some places just outside are included. The Greater London boundary has been aligned to the M25 motorway in places. Outward urban expansion is now prevented by the Metropolitan Green Belt, although the built-up area extends beyond