Castle Vejer is a 9th-10th century Moorish fortress with an Islamic gate located on the highest point of Vejer de la Frontera in Cádiz province. Originally built with a rectangular 74-by-22-meter floor plan and three towers, it was modified extensively in the 15th and 16th centuries by the Dukes of Medina Sidonia, who added a porticoed patio and modernized the interior. Declared a national monument in 1931, the castle features an ethnographic museum and commanding views across the surrounding countryside and Mediterranean coast from its restored battlements. The complex showcases the layered history of Andalusian border fortifications.