Cities

CityRail - Operates the Sydney underground system. Includes detailed timetables, trackwork announcements, station descriptions, and ticket and fare information. Also provides event information, performance statistics, and other operational reports.
Daegu Metropolitan Subway Corporation - Describes the facilities and stations, the SMSC's vision and construction updates, safety and service features, and management information for the city's underground railway system.
Delaware River Port Authority Transit Corporation (PATCO) - Commuter service connecting Philadelphia and southern New Jersey. Site provides map and schedule, fares, news, parking and bicycle guidelines, history, and administrative information.
Delhi Metro Rail Corporation - Route maps, travel tips, and construction projects described.
Flickr: London Tube - Collecting shots of the Tube and London Underground Tube stations.
Flickr: Vancouver Transit - Photos and discussion about Vancouver's transit system, including buses and trolleys, SeaBus, SkyTrain, and the West Coast Express.
Incheon Rapid Transit Corporation (IRTC) - Provides maps of the Incheon and Metropolitan subway system as well as background facts and operations overview.
Metro Bielefeld - History, photo gallery, and map of the German subway system.
Metro Bilbao - General information about the transit system of Bilbao, Spain.
Metro Bilbao News - News, facts, and information for the transit system of Bilbao, Spain.
Metropolitano de Lisboa - Official web site of the Lisbon, Portugal underground railway. Network maps. Information and news. Facts and figures.
Metropoliten of Baku - History, station list, and map. Additional content available in Russian and Azeri.
Moscow Metro Photos - Photographs and VR panoramas of some of the metro stations in the Russian capital.
Naples Metro System - Contains information on the system, its development, lines, and stations, with related places of interest. In English and Italian.
Novosibirsk Subway - Map, station photogtaphs and facts, and information about Novosibirsk provided.
The Pyongyang Metro - Information about the subway system in the North Korean capital. Includes maps, news, photographs, and pictures of former Berlin U-Bahn trains now used in Pyongyang.
STM: Montréal Métro - Includes interactive map, PDF guide to the 'underground city,' fares, and an explanation of the station chime system.
Subway.com.ru - Historical and modern photographs of the New York City, Montreal, and Moscow subway systems.
Tehranmetro - Official site of the Tehran Urban and Suburban Railway Co. (TUSRC). Schedules and maps, tickets and fares, and information about accessibility, services, and construction projects.
Teito Rapid Transit Authority (TRTA) - Fare information and major station guides for the TRTA portion of Tokyo's subway system.
Tyne and Wear Metro - Official site for the subway system of Sunderland and Newcastle in North East England, UK.
Umka's Subway Maps - Cities around the world listed with their maps presented full-size.
Vienna Subway/Metro - Contains maps, timetables, information about fares, tickets, and history of the metro in Vienna, Austria.