In 1250, a foral (charter) attributed to King D. Afonso III was issued to Redondo. At the same time, the king ordered the construction of a castle over the ruins of the ancient Roman fortress.
The castle was part of the northern Alentejo fortifications restructured by King D. Dinis that were donated to members of the nobility during the late medieval epoch, representing significant alterations during the Manueline era. By order of King D. Dinis, in 1312, the castle was reconstructed, during the same epoch as the erection of the keep tower and the fortification wall and towers. On 27 April 1318, the foral was reconfirmed by King D. Dinis.
In 1418, King D. John conceded privileges to the castle and obligated that travellers between Alandroal and Vila Viçosa pass through the settlement, as a way of expanding commercial activities in the town.