USA/ME: Fort Knox
Fort Knox (not to be confused with the one in Kentucky) in Maine is a massive defensive fort built between 1844-69 entirely out of granite. The fort was built to protect the access to the Penobscot River Valley and defend against possible future attacks from the British. The main structure of the fort has 64 guns, plus it had two open water batteries facing the river, each equipped with a shot furnace to heat cannonballs so that they could ignite wooden ships if the ball hit the vessel. The fort is in pristine condition and it’s absolutely intact – all rooms, stairs, gun batteries, basement and so on and so forth. And the best part – you most likely will be the only people to explore this and relive the history!