Stone-Drop

This seemingly innocuous feature of the keep appears from the outside to be a decoration. A section of the wooden wall of the first floor of the castle extends over the stone wall in a slightly curving flare. The unexpected element is that the floorboards are removable and reveal a trapdoor that would allow defenders to observe intruders attempting to scale the steep castle wall from the moat below. Defenders could counterattack by dropping stones or boiling water on the intruders, or by shooting them with arrows or guns.