The Santa Clara buildings were originally built by King Alfonso XI as his palace in 1344. His son Peter the Cruel had it embellished by Mudéjar artists, beautiful works at Santa Clara, though on a much smaller scale than they did in the Alcázar of Seville. The facade, a lovely small patio, a chapel and the baths remain of Peter the Cruel's palace. Blanche de Bourbon was held here after her abandonment by Peter for María de Padilla in 1353. The former portal, blocked off now, has a particularly fine Mudéjar doorway. In 1363 he ceded Santa Clara to two of his daughters by María de Padilla. They turned it into a convent, but it retained its role as a royal palace.
Santa Clara convent's saddest association is with Joanna I Queen of Castile and Aragon, the daughter of Isabella I of Castile and Ferdinand II of Aragon, widow of Philip I of Castile and mother of his six children including Charles V, Holy Roman Emperor - popularly known as Juana la loca (Joanna the mad) - who was confined here for almost half a century until her death in 1555.
References:The Château de Foix dominates the town of Foix. An important tourist site, it is known as a centre of the Cathars. Built on an older 7th-century fortification, the castle is known from 987. In 1002, it was mentioned in the will of Roger I, Count of Carcassonne, who bequeathed the fortress to his youngest child, Bernard. In effect, the family ruling over the region were installed here which allowed them to control access to the upper Ariège valley and to keep surveillance from this strategic point over the lower land, protected behind impregnable walls.
In 1034, the castle became capital of the County of Foix and played a decisive role in medieval military history. During the two following centuries, the castle was home to Counts with shining personalities who became the soul of the Occitan resistance during the crusade against the Albigensians.