5. Brooklyn Heights’ Secret Subway Ventilator

Many of our readers may already know about the secret subway ventilator on 58 Joralemon Street in Brooklyn Heights. The building sits innocently among its neighbors on this residential street, but its slightly off red facade and blacked-out windows reveals its decoy. In fact, behind the faux facade is a subway ventilator and emergency exit that serves the 4/5 trains running in the tunnels below. Passersby might not be able to peer inside the structure, but residents can definitely identify the structure from the faint cacophany coming from ventilator blades inside. The site also leads to the world’s oldest train tunnel, the Atlantic Avenue Tunnel, built in 1844.