Castle of Sos del Rey Católico Monument · Sos del Rey Católico, Cinco Villas, Zaragoza The castle of Sos del Rey Católico, also known as the castle of the Peña Felizana, stands at the top of the historic ensemble of this town of the Cinco Villas, in Zaragoza. It preserves the keep, square in plan and about six metres to a side, raised in the 11th century, and a walled enclosure of reduced size completed by Ramiro II, with a circular tower fitted with arrow slits and an access gate with a round arch. The ensemble is today in ruins; excavations carried out on the esplanade have brought to light remains of old rooms and walls. It has been listed as a Bien de Interés Cultural (Spain's highest level of heritage protection) since 2006. Photo: Ecelan (CC BY-SA 4.0) What to see and do in Sos del Rey Católico