An original Columbiad cannon barrel in a first level Fort Delaware Casemate with open embrasure.
Notice the tracks below the embrasure for aiming and maneuverability.
Pea Patch Island, Delaware
 

A replica Columbiad cannon in a second level casemate.
Again, notice the tracks for assisting in aiming the cannon.
Pea Patch Island, Delaware
 

A Columbiad Cannon at Fort Darling on the James River VA at Fort Darling at Drewry's Bluff Virginia on the James River.
Courtesy of the US Library of Congress.