The Princely Abbey of Corvey ( or ) is a former Benedictine abbey and ecclesiastical principality now in North Rhine-Westphalia, Germany. It was one of the half-dozen self-ruling princely abbeys of the Holy Roman Empire from the late Middle Ages until 1792 when Corvey was elevated to a prince-bishopric. Corvey, whose territory extended over a vast area, was in turn secularized in 1803 in the course of the German mediatisation and absorbed into the newly created Principality of Nassau-Orange-Fulda. Originally built in 822 and 885 and remodeled in the Baroque period, the abbey is an exceptional example of Carolingian architecture, the oldest surviving example of a westwork, and the oldest standing medieval structure in Westphalia. The original architecture of the abbey, with its vaulted hall and galleries encircling the main room, heavily influenced later western Romanesque and Gothic architecture. The inside of the westwork contains the only known wall paintings of ancient mythology with Christian interpretation in Carolingian times. The former abbey church was listed as a UNESCO World Heritage Site in 2014. History of the abbey Foundation and early years In the Saxon Wars which lasted more than thirty years after 772, Charlemagne, king of the Franks, was eventually victorious, adding the Saxon territory to his empire and starting the Christianisation of the Saxon people. To that end, bishoprics were established (at Hildesheim and Halberstadt). In addition, the idea of setting up an abbey in Saxony was first mooted during Charlemagne's reign. However, the plan was only implemented under his son, Emperor Louis the Pious, who announced the creation of an abbey east of the river Weser at a synod in Paderborn in 815. This was located at a place named Hethis. Although there is some uncertainty over the exact location, it is today thought to be near . The first monks arrived in 816 from the Benedictine abbey from Corbie Abbey in Picardy. They set up a Probstei, a subsidiary of the motherhouse. Due to the inappropriate location chosen, the monks chose to move in 822 – to the current location near what was then called Villa Huxori. The new house became known as Nova Corbeia (Latin for the "new Corbie"; Old German: Corvey ). The first abbot of Corvey was a cousin of Charlemagne, Adalard of Corbie. Ansgar, who later became the "Apostle of Scandinavia", founded the abbey school in 823. The abbey library was established with