Scotland travel: Edinburgh Castle "Prisoners of War" exhibition. "In the late 18th and 19th centuries, parts of the castle were used as a jail to hold captured sailors of many nationalities. Among them were citizens of the newly independent USA, still seen as rebels by the British...[this] experience in the castle vaults vividly recalls the conditions the captives endured." (From the guide to Edinburgh Castle pamphlet.) We know that the dungeon of Dalhousie Castle housed it's fair share of prisoners, and Culzean Castle probably held captives in it's cliffside caves.