Armed with a site plan to guide his search, Plaquemines Parish historian Rod Lincoln recently led his latest expedition through Fort St. Philip in search of a bomb-proof hidden amid the historic fortification's 60 acres along the Mississippi River's east bank.

Likely built during the mid-1800s, the bunker-like structure where soldiers sought refuge during bombardments has been overtaken by brush and debris like much of the outpost.

"It's a shame," Lincoln said to a small entourage of historians and history buffs. "We know it's here somewhere. We just have to find it. It's so overgrown here, it's hard to see where everything is."