We were issued miner's hats and led down beneath a metal grate in the middle of a wintry Upper West Side street. All day long our guide signaled to trains with a special lantern from abandoned stations and secret tunnels as we moved beneath the city.
Regular trains would stop and we would climb aboard with sooty faces and funny hats. Passengers not used to stopping at the unlit abandoned stations kept asking "Oh my God. What happened to the train you were on?"
The once yearly tour is hard to get a spot on--I had a friend who was a donor to the Transit Museum....
Don't miss City Hall station at the link below, it is a particular delight.
Link: Abandoned Stations.