In 1236 the city was captured by Ferdinand III the Saint, and Córdoba entered the Christian world again. The Great Mosque became the Cathedral and new defensive structures were raised, among them the Alcazar de Los Reyes Cristianos (Fortress of the Christian Rings) and the Terre Fortaleza de la Calahorra, as befitted its role as a frontier town under constant threat of attack from the Moors.
With the re-establishment f Christian rule over the whole of the Iberian peninsula Córdoba lost much of its political and intellectual importance. It did, however, preserve an important commercial role, because of the proximity of the copper mines of the Sierra Morena.