City Hall Station is the original southern terminal of New York's first subway line, closed to regular service since 1945 but still one of the system's most beautiful spaces. Its tiled arches, skylights, and chandeliers are a sharp contrast to the working Brooklyn Bridge-City Hall station beside it.
The easiest glimpse is from the downtown 6 train: stay on after Brooklyn Bridge-City Hall as the train loops through the old station to head uptown again. The New York Transit Museum also runs occasional guided visits, but they are limited and require advance planning.