Fort Knox Bucksport Maine (Was built and never used)
I have been inside the dungeons of this fort.
I would have been a horrid place for Englishmen captured by the rebels...
Some of the holding cells had shallow walls with high ceilings that went onto far hidden passageways. Not sure how they could have kept prisoners in one place. Only adds to the mystique of the place.
Each cell had its breach... Maybe that is my take of the place. But I have been inside.