Would-be burglars attempted to break into Robber's Cave early Thursday morning, Lincoln Police said.
Officers responded to an alarm at the cave site, 925 Robbers Cave Road, around 3:30 a.m. and found someone had broken into a wooden structure over an access point to the cave.
It did not appear the manhole covering the entrance to the sandstone tunnels had been moved.
Nothing was taken or vandalized in the cave, but there was about $20 in damage to the wooden structure, police said.
Inside Robber's Cave
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Drawings, names and dates back to the 1800s blanket the walls of Robbers Cave, now part of the Blue Blood Brewing Company.
Blue Blood Brewing's owner Brian Podwinski (right) and partner and contractor Sam Manzitto discuss the work they still need to do to entrance of Robbers Cave.
Blue Blood Brewing turned an original but filled-in entrance to Robber's Cave into an emergency exit to help the company meet city fire codes.
The builders of Blue Blood Brewing's 12,000-square-foot building enveloped the original entrance to Robber's Cave, near 10th and High streets.
Teenage trespassers have used an old wooden ladder to break in to Robbers Cave at the site of the new Blue Blood Brewing building.
Blue Blood Brewing owner Brian Podwinski (left) and partner Sam Manzitto stand in Robbers Cave, the Lincoln landmark they bought as part of the brewery's $2 million expansion. The cave will be open in the next two weeks, Podwinski said.
Blue Blood Brewery will use a dead-end tunnel with a shaft leading to the surface as designated bat habitat in Robbers Cave.