UPDATE: Currently closed by New York department of transportation
Unbeknownst to the thousands of people who walk and drive along the busy streets of downtown Brooklyn every day, they are treading on a 165-year-old secret. At 17 feet high, 21 feet wide and 1,611 feet long, it is a big secret indeed, and one filled with greed, murder, and corruption.
The tunnel, built in 1844 by Cornelius Vanderbilt, was an attempt to avoid incidents of trains striking errant Brooklynites. It was to be the first underground, or "grade-separated," transportation system: the world's very first subway.
The work was done almost entirely by Irish immigrants. According to an 1844 Brooklyn Eagle article, when the Irish workers were told by a British contractor they would have to miss church and work on Sundays, an Irishman pulled a gun, shot the Brit, and the group buried him behind the wall of the tunnel — where presumably his body still resides today. In a corrupt deal, the tunnel was capped up and forgotten by the end of the 1850s.
The Atlantic Avenue Tunnel was rediscovered by a curious young man named Bob Diamond in 1980. Diamond found the tunnel by reviewing microfiche at the local library and locating an old blueprint in the borough president's office. Brooklyn's answer to Indiana Jones, Diamond went down through the manhole, dug through a layer of dirt, and broke down the brick and mortar between him and the tunnel.
For a time, you could tour the tunnel with Bob Diamond. You accessed the tunnel by filing down, one-by-one, through a manhole cover in the middle of busy Atlantic Avenue. Diamond is a wellspring of fantastic stories about the origin of the tunnel and how he came to find it. The tunnel is a marvel, and walking through the 165 year old underground passage was an experience like little else in New York.