[@Scrapula]: Well, the without going into two much detail, the first floor is already down a steep flight of stairs. The only thing on the surface that even marks the castle's existence is a crumbling tower surrounded by the ruined remains of walls. You're already going down to get to the first level, and there is a trap on the stairs which might not be lethal but is rather embarrassing and was probably nasty when there were still active guards about.