11. Wartime Munitions Warehouses
During WWII, American cities carved brick- and concrete-lined warehouses beneath remote outskirts to hold weapons and ammunition.
At Fort Ord, California, miles of tunnels and vaults stored tons of shells under pine forests, keeping them safe from aerial attack.
Some were linked by rail spurs for rapid loading.
Many of these bunkers were sealed with steel blast doors and left abandoned after the wars.
Today, urban historians and hikers explore their eerie passages, mapping hidden military relics.
Learn more via Atlas Obscura.
