A large military catapult which fired projectiles of iron or stone. Roman examples were made up of a framework in which twisted tendons, rope, or leather thongs provided elasticity and force. When the twist was suddenly released, a stone of up to 45 kg in weight could be thrown a considerable distance to batter a wall. The most famous ballista bolt in Britain is that piercing the spine of a man buried at Maiden Castle, Dorset. Ballistaria or ballista platforms can still be detected in some forts. In the later Roman period ballistae were mounted on bastions projecting from fort walls.