You've never been? Oh my. When Union troops occupied the castle they were moving an artillery piece on the main gun gallery and it fell through a weak spot. This opened a hidden passage to an unknown underground space within the walls. The floor was covered in bones. This was later learned to be a Spanish dungeon where several persons were buried alive. This is open to the public and is a bit spooky if you believe the story. I love the old streets and the people in 17th Century clothing that give tours.