This part of Portugal was under Muslim rule for over 400 years. in 1166, the Portuguese forces under the command of King Afonso I conquered Serpa. However, in 1191, the Muslim forces of Almohad retook the city and it’s castle. The region returned to Portuguese rule once more under king Sancho II in 1232. The reconstruction of the old Muslim fortress began in 1295. In 1580, Serpa and its castle fell to the Spanish forces. Later, this castle was neglected in the second half of the 17th century. A powder magazine destroyed one of the towers of the castle after the Spanish withdrawal in 1707.
The wall of the fortress is reinforced by the Keep which is connected with other towers. The castle and its walls are reinforced by turrets and square and semicircular plant towers, topped by merlons prismatic. Towers and defensive walls can be seen which stretch from the castle and around the old town.