The Abbey of San Pedro de Siresa (, ) is a monastery in the Valle de Hecho, (Aragon, Spain). It was constructed between the 9th and 13th centuries, and is the northernmost monastery in Aragon. History Buildings have existed at this site for centuries, possibly back to Visigothic times according to the excavations conducted in 1991. A Roman road (ruins of which remain today) passed nearby, connecting Zaragoza and Berdún (in the municipality of Canal de Berdún) to Béarn (France), through the 1,970 meter pass at Puerto de Palo. In 833, Galindo Garcés (Count of Aragon between 833 and 844) and his wife Guldegrut made donations to build a monastery here. Zechariah became the first abbot, and organized the monastery in accordance with the rules set in 816 in a synod held in Aachen, inspired by the rule of Metz Crodegando. In 852, the traveling monk and scholar Eulogius of Córdoba wrote Guilesino of Pamplona about the splendor of the monastery and its library. Eulogius found and copied Greco-Roman manuscripts there which had been lost in his home Caliphate of Cordoba, including an Aeneid, Latin poetry of Horace and Juvenal, fables by Aviano and The City of God by Augustine of Hippo. A donation completed in 864 granted the monastery all the valley lands between Javierregay (now the town of Puente la Reina de Jaca) to the site of Water Eye, in the Pyrenees, which includes the Subordán Aragon river, today in the municipality of Anso. In the year of his death Galindo Aznárez I (Galindo Garcés' successor, Count of Aragon between 844 and 867) gave the monastery the town of Hecho, head of the valley, as well as dozens of vineyards, cultivated fields and the town of Surba. The monastery also benefited from the restoration of the ancient episcopal see of Huesca, which had disappeared for a long time. Tenth century grants and confirmations of property document the monastery's importance and use of income to acquire new lands. The structure None of the original Carolingian or Reconquista monastery's buildings remain. Only the church, probably rebuilt in 1083, during the height of the monastery's power and wealth, survives. The old Carolingian abbey was reformed in that year, and construction resumed in the middle years of the following century, but eventually petered out. The large building has cruciform design (in the form of a Latin cross). A crypt lies under the