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
Safety on the London Underground train. Several stations on the Jubilee line extension are fitted with platform edge doors, which prevent people from falling or jumping onto the tracks. Terrorism in the London Underground has been a major concern because the Underground's importance makes it a prime target for attacks. Many warnings and several attacks, some successful, have been made on the Underground, the most recent on 21 July 2005, although in that case only the detonators exploded. The most recent attack causing damage was on 15 September 2017, when a man detonated a homemade bomb on a District line train at Parsons Green station.