According to legend The seven castles on the shield of Portugal are traditionally considered a symbol of the Portuguese victories over the Moors, under King Afonso III who is said to have captured seven enemy fortresses in the course of his conquest of the Algarve in 1249. The first was Mértola, the last Cacela.

Called the last unspoiled fishing villages in the Algarve, Cacela Velha is hidden in the open and lovely beaches of the Parque Natural da Ria Formosa. One can still see the fort, that guards the active fishing harbor. The tiny village is quite picturesque perched above the sea and sandbars speak of an age gone by. The local church, the fortress walls and the traditional style of the houses give the visitor a flavor or what life looked like in Algarve in days past.

The next place you come to is Mertóla. It’s a museum town of sorts monuments date back to the roots of Roman and Moorish culture.

Martial extends over the two banks of the river Guadiana and covers an area of more 
than 1,200 square kilometers. 
Before the Roman period, Martial was already a significant commercial axis, because it was the most Northern inland port on the river. It is here that people arrived and settled and that goods that came from the most remote regions of the ancient Mediterranean world circulated. 
It is also here that the river and the roads which brought the bread and the olive oil from the clayey soil of Beja and minerals of Aljustrel and Sao Domingos crossed. The combination of all these factors made Martial an historically important town.

The monuments and landmarks of this past are scattered over the city, still surrounded by the old wall, a kilometer long. Sauntering through the narrow streets you will feel as though you are in ancient times and on every street corner you can feel the history of the Phoenicians and the Moors. Recently, an area of about 600 km2 around Mertóla was declared natural park. Here you can find the black stork and the blue magpie.

The castle of Mértola is located on the highest point of the village. Even though the castle is of Muslim origin, the current building dates from a reconstruction carried out by the knights of the Order of Santiago after the village was taken by the Christians. The most notable feature of the castle is its 30 meter-high keep tower, finished around 1292, which has an inner hall covered with Gothic vaulting. The defences include a city wall, which still encircles the village.