This feature is the main outer perimeter wall of the fortification. It consists of two parallel walls, with the space between filled with rubble and sand to create a walkway around the entire fortification. The outer wall is about 3.26 m high, while the inner wall is about 1.55 m high. The walls are made of andesite stone with lime plaster. The outer wall construction is not made perpendicular, and the top tends tilt to the inside, making the bottom of the wall wider than the top. The wall is about 4.5 m thick at its base. The distance between the outer wall and inner wall is about 3.3 m. There are some embrasures on the outer wall, four embrasure on each side, for a total of 16 embrasure. The embrasure are set at regular intervals around the wall. There is a staircase from the outside that connects with the top hallway attached to the outer wall. There is also a staircase on the inside that is attached to the southeast wall.