Caerphilly Castle Outer Wall

Once you pass through the initial small guard house and cross a small moat, you get to the outer wall, where you experience another drawbridge with a deep (but waterless) hole. Notice on the wall walk there are rectangular holes at every guard turret. These were covered with wood planks that would be removed as you retreated making it difficult for your pursuers to follow you, lest they fall into a deep hole without an exit.