3. There was an abandoned Cobble Hill Tunnel rediscovered in 1980

the Cobble Hill Tunnel
From Wikimedia Commons by Vlad Rud.

The Cobble Hill Tunnel was located under Atlantic Avenue and was built in 1844 as an alternative to the above-ground railroad tracks. Trains would transport goods to and from the waterfront during the 1840s, but the steep hill in the neighborhood often made these rides difficult with heavy cargo. The vaulted tunnel, made of brick, originally ran from the Ferry Terminal to Times Plaza. The tunnel shut down in 1861, though, once New York State banned railroad locomotives from the City of Brooklyn.

In 1980, about 120 years since the City of Brooklyn banned steam locomotives within city limits, Bob Diamond stumbled upon the hidden underground gem. From 1980, he gave tours of the half-mile span until his permit was taken away in 2010. According to the Verge, “He’d lug three plastic orange barricades out to the middle of Atlantic Avenue, pry off the manhole cover with a crowbar, and steady a thin ladder into the narrow shaft, the only entrance to the tunnel. Tourists would line up in the middle of the busy road, descending one by one into a tight passageway.”