Even when you’re not looking for the past, it somehow finds its way into the present. That certainly rang true for workers near New York University’s campus replacing a water main.

As they dug three and a half feet into the ground, they soon discovered two centuries-old burial vaults filled with the bones of between nine and 12 people. Alyssa Loorya, the project's principal investigator, says the vaults were likely built in the late 18th or early 19th century and probably belonged to one of the two Presbyterian churches in the area. Per the Associated Press, officials say Washington Square Park was a potter’s field for yellow fever victims in the early 1800s.

"We knew we could be encountering remains or other items in this area," said Thomas Foley, an associate commissioner with the city's Department of Design and Construction. "We'll do some exploring to discover what other lanes we might have."

Loorya added: "You never know what you can find beneath the city's streets. You bury people to memorialize them, and these people were forgotten."

The bodies are currently unidentified but workers will search old newspapers, death records and church archives to figure out who they are if possible. As for the water main, project engineers are working on a new route in order to respect the city’s policy of leaving burial grounds undisturbed.