Castle of Alcocer, Medieval fortress near La Mora Encantada in Ateca, Spain

The Castle of Alcocer is a ruined fortified Muslim village at the La Mora Encantada site in Ateca, Zaragoza. Its most visible remain is a large, worn rammed-earth tower with a base of about 10 by 16 metres. Excavations have uncovered wall foundations around 40 cm high, rooms, at least two silos and a small circular tower built on rock.

The fortress dates from the Muslim occupation period and takes its name from the Arabic word al-Quṣayr, meaning small palace. It was built and later abandoned during medieval conflicts between Muslim and Christian forces.

The fortress is mentioned in medieval Spanish epic poems and represents a key location in El Cid's military campaigns. It bridges the Muslim past with Christian conquest history in this region.

The site lies on the left bank of the Jalón, opposite the hill known as Otero del Cid or Cerro de Torrecid, which held El Cid's camp. Access is over uneven ground with exposed foundations and loose rammed earth, so wear sturdy shoes. The remains are protected as a Bien de Interés Cultural; check access conditions with the Ateca authorities before setting out.

Excavations found the foundations of at least two silos and a circular tower built directly on the rock, remains that led researchers to interpret the site as a fortified village rather than a castle. The name Alcocer comes from the Arabic al-Quṣayr, meaning "the small palace".