Sanita Hills was originally made for NYC sanitation workers (hence the name) by pulling old NYC rail cars, nicknamed Pullmanettes, into the woods and converting them into cabins. The cars came from the old Second and Third Avenue El elevated railway lines in NYC. Later the camp was taken over by the Boy Scouts before eventually being abandoned. At some point all of the cars were cut up and removed, except one.  These are photos of what remains of the camp at Whaley Lake.

More information:  Abandoned Hudson Valley

Locations:
Remaining car – Google Maps (41.549786, -73.655748)
Some of the camp – Google Maps (41.556562, -73.653208)