sentences:  In the Phillipienne castle other towers, usually round were placed at the corners and along the walls, close enough together to support each other.The walls had two levels of walkways on the inside, an upper parapet with openings ("créneaux") from which soldiers could watch or fire arrows on besiegers below; narrow openings ("merlons") through which they could be sheltered as they fired arrows; and floor openings ("mâchicoulis"), from which they could drop rocks, burning oil or other objects on the besiegers.The upper walls also had protected protruding balconies, "échauguettes" and "bretèches", from which soldiers could see what was happening at the corners or on the ground below.