City Hall Subway Station
The Dark Manhattan's version of what (in our home universe) is the abandoned IRT station at New York City's City Hall: the area where Nita and Kit find the Eldest and the Book of Night with Moon.
This station started construction in 1900 as a showplace station for New York City's first subway project. It was in service from 1904 to 1945, at which time -- due to declining rider numbers caused by the greater convenience of other nearby stations -- it was closed. Its beautiful Guastivino arches and tilework have languished for a long time in near-darkness, its skylights still wearing the blackout paint applied to them during World War II. Some of these skylights can still be glimpsed in the surface of the parking lot outside of City Hall.
Though an alert (and sneaky) subway rider can still catch a glimpse of the old station while riding a late-night number 6 train through the "turn-around" loop at the end of the line, there are no tours or other ways to see the place except through various online photo collections. (And normally riders are not allowed on the trains while they're being turned around in the loop, so sneaking on or otherwise hiding is required. And not recommended.) Some images, and more information about the station's history and architecture, can be found at its Wikipedia entry.
Probably the best of the independent online photo collections is at the New York Subway website; though it would also be a mistake to miss City Hall Station's entry at Joseph Brennan's labor-of-love website, Abandoned New York. This site also covers many other lost or strayed parts of New York's rapid transit system. (See also the "Forgotten New York" site here, and (ranging a little further afield) the links page at Modern Ruins. (SYWTBAW)
(See also: Subterranean ecologies: New York urban ecologies: Lexington Avenue local.)