The Vertex Parapets is a fortified complex in Jaulín, built during the Spanish Civil War by the rebel army in front of the Vertex of Sierra Gorda, position of the Republican Army,1 in the battle of the Ebro. Its purpose was to stop the advance of the Republican Army in the direction to Zaragoza from the south.
It is located on both sides of the road that goes from Jaulín to Fuendetodos, next to a geodesic vertex of the National Geographic Institute, hence its name. It consists of four bunkers of the type known as a squad post. These posts are rectangular in shape and have loopholes for about twenty riflemen and a machine gun nest in the corner facing the enemy; in the center they have a warehouse and rest area. According to the figure inscribed on them, they were built in 1937 by the company of sappers "Los Barbis".