Urban rail, though it's not always under ground. Not the sandwich shop (though you can find said shops in some of such places).
Many of the great cities of the world have subway systems, metro systems, underground systems, what have you—they're trains underground is what counts. They tend to be part of the lifeblood of the city, an element of its character, a point of pride (or occasionally shame) for its citizens, and a record of its history. They develop their own unique cultures and quirks. In short, they are kind of awesome...which is why we made this index.
Subway systems of the world
Africa
- Algiers Metro
- Cairo Metro
Asia-Pacific
- Almaty Metro
- Bangkok SkyTrain and Metropolitan Subway
- Chinese Subways
- Beijing Subway
- Hangzhou Metro
- Shanghai Metro
- Shenzhen Metro
- Delhi Metro
- Hong Kong MTR
- Jakarta MRT
- Melbourne Metro
- Osaka Subway
- Seoul Metropolitan Subway
- Singapore MRT
- Sydney Trains Metro And Light Rail
- Dankal (Tel Aviv; actually a tram with an underground section, though a proper metro is planned as part of the system)
- Tokyo Subways (Tokyo Metro, Toei Subway, and other lines frequently used)
Europe
- Amsterdam Metro
- Metro De Barcelona
- Berlin U- and S-Bahn
- Brussels Metro
- Budapest Metro (and other public transportation)
- Copenhagen S-Tog and Metro
- Frankfurt U And S Bahn (actually operates as light rail, known as "Stadtbahn" in German)
- Glasgow Subway
- Hamburg U And S Bahn
- Helsinki Metro
- Lisbon Metro
- The London Underground
- Metro De Madrid
- Milan Metro And Linee S
- Moscow Metro
- Munich U And S Bahn
- Nuremberg U Bahn
- Novosibirsk Metro
- Oslo T Bane
- Le Métropolitain (Paris)
- Prague Metro
- Rome Metro
- Rotterdam Metro (includes Randstad Rail, which is light rail)
- Saint Petersburg Metro
- Stockholm Metro
- Turin Metro
- Tyne & Wear Metro (Newcastle—upon―Tyne & Sunderland; actually light rail)
- Vienna U And S Bahn
- Warsaw Metro and Urban Rail (covering the Warsaw subway, SKM and Warsaw Commuter Railway)
The Americas
- Brasília Metro
- Buenos Aires Metro
- Caracas Metro
- Lima Metro
- Medellín Metro
- Mexico City Metro - second biggest Metro in the Americas based on ridership (the biggest is in NYC)
- Montreal Metro
- Panama City Metro - opened in 2014 the oldest Metro in mainland Central America
- Rio de Janeiro Metro
- Santiago Metro
- São Paulo Metro
- Subways of the United States
- Toronto Subway
- Tren Urbano (San Juan, Puerto Rico)
- Vancouver SkyTrain
