Its structure follows the same architectural lines characteristics of the Knights Templar, the castles of Almourol, Monsanto, Pombal, Tomar and Zezere, his contemporaries.
King Sancho I (1185–1211) granted a foral charter in 1201 in order to encourage the settlement and defence of the land.
His successor, King Alfonso II (1211–1223), confirmed this charter in 1219, renaming the village with the current place names (Idanha-a-Nova), to distinguish it from the old Idanha (hereinafter Idanha-a -Velha), eighteen kilometers away.
In the late fifteenth century, King Manuel I (1495–1521), was surprised with the difference in the development of the two Idanhas (1496) and in June 1510, recognizing the progress of Idanha-a-Nova, granted him New charter.
At this time, the town and its castle, including the layout, was recorded down by Duarte de Armas in his Book of Fortresses in 1509.