There are many mysteries that lie beneath New York City, not the least of which are part of the transit system. I swear I feel the Second Avenue Subway rumbling beneath my apartment building (there are functional tracks). The Hoyt-Schermerhorn station in Brooklyn has a whole platform for unused tracks (as does the Delancey/Essex Street's JMZ line). A few years ago they discovered an entire tunnel under Atlantic Avenue in Brooklyn that you can only access now through a manhole.
The only subway station that I've seen closed since I've moved to the city was demolished as a result of the World Trade Center collapse, but there are a few others that are still standing. (The Transit Museum occupies such a station.) If you ride the 6 train downtown between 23rd St. and Union Square and press your face against the window, you can catch a glimpse of a very dirty 18th St. station. And if you stay on the 6 train at Brooklyn Bridge, the last stop, you might catch a glimpse of the closed City Hall station when the train turns around on the looped track to come back to Brooklyn Bridge on the uptown platform.
This weekend the Transit Museum hosted a guided tour through the old station, a much better look with the 11 chandeliers lit up. There are three skylights in major disrepair that also illuminate the platform, much of their original leaded glass shattered, blackout paint covering the remaining bits. When it comes down to it, it's a small station, only one platform, two entrances (one still filled with concrete), and a mezzanine with a big blank space where the ticket booth used to stand.
Another skylight above ticketing area, whose tar has been removed as part of the restoration of the station. Some of the bulbs need replacing but it gives a real indication of the original splendor of the station, something that was unusual for the IRT line even at the time.
View of the City Hall archway to the single staircase, leading up to the mezzanine, with the center skylight (and lead glass in tact).
As much as they've cleaned up the station, everything was still covered in black soot, and it's no wonder: the track is so curved that it not only creates a huge gap between the train and the platform, but also a horrible screeching sound that gives Union Square a run for its money for shattered eardrums. And steel dust. Eroded tracks. Black soot.View of the platform facing downtown, with the gorgeous vaulted Guastavino arches looming above, illuminated by lit chandeliers.
It's too bad that the station was closed to the public in the 1940s, but it wasn't very popular back then. Brooklyn Bridge was more of a depot, a gateway to Brooklyn, and it was just steps away anyway (as are many of the train stations in Lower Manhattan, frankly). And Brooklyn Bridge could accommodate the longer 10-car trains, whereas City Hall's platform was too short (and not easily extendable).
There's a similar phenomenon with the South Ferry station, where for years you've had to be in the first few cars in order to get off there (as I experienced during my first trip to the Staten Island Ferry in 1997). They're actually doing major construction on that station to finally extend the platform...After 60 years...
The Transit Museum is hosting another of these tours in February, which costs only $20 but you have to be a member of the museum. Personally I think it was totally worth signing up for the membership just to get into the City Hall station, which I've been dreaming about for years.
If you want to do some exploring on the outside of the station, get out at the City Hall station on the R/W line, or the Brooklyn Bridge station on the 4/5/6 to Brooklyn Bridge. Walk downtown past City Hall, past the locked gates, to the public entrance of City Hall Park (either on the east or the west side). Towards the west side of City Hall, across the way from the police booth, there's a black subway entrance just like the green ones you see all over the city - we're pretty sure that's the functional "emergency exit" to the closed City Hall station. If you look on the sidewalk right by the police booth, and also in the grassy park to the left, you can also see skylights embedded into the concrete.
The most obvious of the skylights that you can see in City Hall park. This is the only one in the grass.
Here's a diagram that might help you find your way. We didn't find the round skylight over the ticket booth but there's such tight security over there, we didn't really have free roam over the park...