The glacis is a soft and clear slope that precedes a fortress moat, is dominated by the ramparts and other fortifications, from which can be fire upon him and served as a parapet to the covered way.The covered way was the desenfilado space of the direct fire of the enemy which is situated along the trench to facilitate the defense of this. It forms the covered way a defensive line between the slope of the glacis and the edge of the counterscarp. The covered way has a perimeter of 3.120 m.