After 1070, Loarre became increasingly important. In 1073, King Sancho 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. By comparison with other monuments, however, it is also clear that the building and decorative program continued into the 12th century.
The outermost walls of the castle and their eight towers were erected in the 13th or 14th century.