I’ve been going overboard studying the nyc subway recently. The current system is only half of what was originally planned to be built. The amount of abandoned tunnels, abandoned stations, shell stations, bell mouths, and provisionals is amazing. There are parts of the tunnels not even the MTA knows exists. I have always wanted to explore the tunnels but that seems like something you need someone to show you. Gotta worry about getting hit by a train, touching the third rail, getting your foot stuck in a track switch, getting seen by train operators and cops, plus motion sensors in emergency exits and pump rooms and vent shafts.
hipsters and the media gave away the location of the abandoned Chinatown tunnel from the 70s and gave away the location of the south 4th street shell station. Fortunately the street art in the shell station was dissed before the city sealed it off. Both these places are now permanently sealed shut.