From Wikipedia.

The Castle of Loarre is a Romanesque Castle and Abbey located near the town of the same name, Huesca Province in the Aragon autonomous region of Spain. It is one of the oldest castles in Spain. The castle was built largely during the 11th and 13th centuries, when its position on the frontier between Christian and Muslim lands gave it strategic importance. The first of the two major building programs began circa 1020, when Sancho el Mayor (r. 1063–94) reconquered the surrounding lands from the Muslims. In 1073, King Sancho Ramírez installed a community of Augustinian canons, and it was from Loarre that he prepared for the conquest of Huesca in 1094. In 1097, however, his successor, Peter I of Aragon and Navarre, donated all the goods of Loarre to a new royal monastery at Montearagon. This evidence suggests that the second major construction program was undertaken between 1073 and 1097, and much building evidently does date from this period.