Volume 1 takes place in the PATH (Port Authority Trans-Hudson) system.

Volume 3 continues the World of Subways series with the Circle line service of the London Underground.

The Circle Line covers 27 km (16.8 mi) of track and 35 stations, including the extension to Hammersmith, that runs above and below ground through London.

Despite the fact that Aerosoft, the publisher of the series, announced that volume 4 would be set on a line on the Paris Métro,[3] TML-Studios publicly released pictures and information that Volume 4 will instead be set on the New York City Subway system in New York City, based on the 7 service.

Instead, it is set in the late 1980s-early 1990s, when the R33S and R36 subway cars were still operational, and prior to the opening of 34th Street–Hudson Yards on September 13, 2015.