Survival blankets and crackers dating back five decades to the Cold War have been found in a long-forgotten storage room under New York's Brooklyn Bridge.
Officials believe the stash, discovered during a structural inspection, may be one of many created in the US in the 1950s amid fears of a nuclear war.
The provisions include 350,000 "Civil Defense All Purpose Survival Crackers", medical kits and now-empty water drums.
"This is modern American history," said city transport official Iris Weinshall.
"People were worried, they thought we were going to go to nuclear war."
Concealed in the depths of the bridge's Manhattan side, the sealed tins of crackers are dated 1962 - when the Cuban missile crisis brought the world to the brink of nuclear conflict.
Other items are stamped 1957, the year the Soviets launched the Sputnik satellite.
Boxes of paper survival blankets are marked "For Use Only After Enemy Attack".
The stash was discovered in the foundations of Brooklyn Bridge
A box of tags is provided for people to write down their name, address, next of kin and type of medical help needed.
The city has said it will turn over the space to the Civil Defense Museum and historians after an inspection by health officials.
It is still not known whether the supplies were intended to be used at the bridge or were merely placed in storage there and forgotten.
Joseph Vaccaro, one of the workers who stumbled across the cache, added: "This is certainly the most historically significant thing that we've ever found."
Cold War expert John Lewis Gaddis, of Yale University, agreed that such shelters, though common in the 1950s, are rarely uncovered now.
"Most of these have been dismantled, the crackers got mouldy a very long time ago," he told the Associated Press news agency.
"It's kind of unusual to find one fully intact - one that is rediscovered, almost in an archaeological sense."