The Cornwallis Cave.

Cornwallis “cave,” a cavern created by stone quarrying for building material, was once believed to be the “grotto” into which British General Cornwallis retreated to avoid bombardment during the Revolutionary War battle. Subsequent research suggested this is likely a legend. The cave was used for potato storage during colonial times and later for storage of Confederate munitions during the American Civil War in 1862. Large, visible recesses were cut into the front wall by Confederate forces to install support beams for a plank roof and walls that were then covered with earth to protect the munitions from Union warships offshore. The gated cave has since fallen into disrepair as a result of the natural processes of weathering and erosion.  The possibility of stone falling inside is one of the reasons it is gated off.