The fortified system, built in the 13th century, was extensively remodeled in the early 15th century, adapted and expanded in the 17th and 18th centuries and partly rebuilt in the second quarter of the 20th century. Although it is incomplete and several ancillary works have disappeared, it is nevertheless one of the most important sets of medieval military architecture in Portugal. As a whole, it presents a floor plan adapted to the terrain. The wall integrates several doors, surrounds the old town area, with about 660 meters and an area of 3 hectares. The interior space of the village fence is divided into four areas. Two axes in the east-west direction connect the Porta de Sto. António with the gate of the Sun. It is the street of the citadel. In the center is the Church of Sta. Maria and Domus Municipalis. The Church's presence in the center of the fortified space underscores its importance.