The IND Subway connecting 6th Avenue, Manhattan and Church Avenue, Brooklyn, opened on July 1, 1933 (and was later connected to the Culver El in the 1950s). Along this line, some very interesting architectural “diversions” from the usual IND method can be found, like the elevated section (the only one built for the IND) taking the train above the Gowanus Canal and necessitating two recently-renovated stations at Smith-9th and 4th Avenue.
Little-noticed are a pair of subway entrances built along the exterior Prospect Park fence at the 15th Street station, one on Prospect Park West and another at Prospect Park Southwest, both on either side of the Bartel-Pritchard Square traffic circle.
What I’m unsure of is whether the architects exactly matched the stone fence for the new station, or if the new fence was built when the subway came here in 1933.
Also notice the twin lamps illuminating the entrance. One lamp retains the old lantern-style luminaire it had in 1933, but the other one has a green globe, placed there in the 1980s, whose color indicates the station is always open 24/7. This situation is repeated for the station entrance on Prospect Park Southwest.