Though built in 960 on the orders of Cordoban caliph Abd ar-Rahman III, this restored fortress is named after Reconquista hero Guzmán El Bueno. In 1294, when threatened with the death of his captured son unless he surrendered the castle to Merenid attackers from Morocco, El Bueno threw down his own dagger for his son's execution. Guzmán’s descendants later became the Duques de Medina Sidonia, one of Spain’s most powerful families. Above the interior entrance, note the 10th-century castle-foundation inscription.
You can clamber up the castle's ramparts and, in the plain church, admire the excavated remains of Roman-era walls unearthed in 2010. The castle also runs occasional guided tours.