In a dominant position on the highest hill in the region, the castle housed originally in its walls the village that, developing, expanded by the North slope. It is said that this castle Vasco da Gama finalized the plans for your trip to India.

At the time of the Christian reconquest of the Iberian peninsula, the town was conquered by the Portuguese forces under the command of King Sancho I (1185-1211). Aiming its repopulation and defense, the sovereign granted him Foral Charter in 1203. It is believed that the construction of the medieval castle has been started at this stage.

At the time of King Dinis (1279-1325) were launched major reforms in the town’s defenses, including the construction of the fence of the village, completed in 1365.

Established Avis Order, the Montemor-o-Novo domain constituted landlord the Constable D. Nuno Alvares Pereira.