The Alcázar de los Reyes Cristianos (Spanish for "Castle of the Christian Monarchs"), also known as the Alcázar of Córdoba, is a medieval Alcázar located in the historic centre of Córdoba, next to the Guadalquivir River and near the Grand Mosque. The Alcázar takes its name. The fortress served as one of the primary residences of Isabella I of Castile and Ferdinand II of Aragon.