Located in the parish of Seda, in the heart of the Alentejo, the ruins of the walls that surrounded the ancient castle of Seda remain determined to preserve their ancient history.
Without official evidence, some studies point to the existence of a castro of the Lusitanian tribe, occupied by Roman troops who would have erected a fortification there. The Roman presence in the region is well-known, and easily attested to by the Vila Formosa Bridge (1st and 2nd centuries), milestones, and the military road that would have connected Lisbon to Mérida.
In 1160, King Afonso Henriques conquered the village, which at the time was called Arminho, from the Moors and donated the fortification to the Templars. This is the date that marked the beginning of the village's original enclosure. During the reign of King Afonso III, the village was handed over to the Order of Aviz and was later elevated to the status of a town, even serving as the municipal seat until 1836.
The castle, however, gradually lost importance, and only a section of medieval wall, reinforced with turrets, has survived to this day. It has been classified as a Property of Public Interest since 1982.