2 The Atlantic Avenue Subway Tunnel

This creepy place is not for everyone, but if you are bold enough to visit the oldest subway tunnel in the world, you are welcome. Situated within the Brooklyn Heights, Cobble Hill Historic Districts, and U.S. Historic District, the Atlantic Avenue Subway Tunnel was built 1844, rediscovered in 1980 and is now closed to the public, albeit there are some tours that can help you explore this mysterious spot.