On approaching this impressive eagle's nest, one is struck by the site's beauty and calm. In the 11C, Sanche Ramirez, King of Aragon and Navarre, extended this impregnable fortress at 1,100 m altitude, installing a monastery here. Once past the wall, flanked by circular towers, you are greeted by an immense panoramic view over the Ebro depression. The massive keep, a fine vaulted staircase and the 12C Romanesque church are worthy of note.