A mysterious, 3,000-pound safe has been unearthed from the parking lot of a Chicago synagogue — but officials there have decided not to let their curiosity get the better off them.

“We’re excited about this piece of Chicago history, but we have no plans to open it at this time,” Anshe Emet Synagogue in Lakeview said in a statement, without offering further explanation.

The safe was discovered by construction workers who were digging in the synagogue parking lot in June, the Chicago Tribune reported.

“A few of us were going to haul it off and not tell anybody, and split it up whatever we could find,” Jay Quinn, a construction site superintendent, told CBS Chicago. “We thought better of it.”

The synagogue made an attempt to get inside, posting a video on June 26 of a failed attempt by a locksmith to drill into its 18-inch-thick door.

“It’s a type of safe that was designed to make it even harder to break into,” said Rebecca Graff, an assistant professor of anthropology at Lake Forest College who specializes in 19th- and 20th-century Chicago urban archaeology. Experts said the safe was likely manufactured around 1906.

The story of the safe surfaced on Twitter, which led to one user claiming it’s “an old and very battered Ely Norris” cannonball safe.

The unopened safe remains at the construction site.

Chicago is no stranger to mysterious safes.

In a live two-hour televised special, Geraldo Rivera opened a secret vault in the Lexington Hotel owned by mobster Al Capone, only to discover several empty gin bottles and dirt.

“We tried to call Geraldo, but he wasn’t available,” said Matthew Tobias, director of security and safety at the synagogue.