One of the oldest cathedrals in Europe, it was constructed by order of the emperor Charlemagne, who was buried there in 814. From 936 to 1531, the Palatine Chapel saw the coronation of thirty-one German kings and twelve queens. The church has been the mother church of the Diocese of Aachen since 1802 Charlemagne began the construction of the Palatine Chapel around 796, along with the building of the rest of the palace structures. The construction is credited to Odo of Metz. The exact date of completion is unclear; however, a letter from Alcuin, in 798, states that it was nearing completion, and in 805, Leo III consecrated the finished chapel. A foundry was brought to Aachen near the end of the 8th century and was utilized to cast multiple bronze pieces, from doors and the railings, to the horse and bear statues. Charlemagne was buried in the chapel in 814. It suffered a large amount of damage in a Viking raid in 881, and was restored in 983. After Frederick Barbarossa canonized Charlemagne, in 1165, the chapel became a draw for pilgrims. In order to sustain the enormous flow of pilgrims in the Gothic period a choir hall was built, in 1355, and a two-part Capella vitrea (glass chapel) which was consecrated on the 600th anniversary of Charlemagne's death. A cupola, several other chapels and a steeple were also constructed at later dates. It was restored again in 1881,when the Baroque stucco was removed. During World War II, Aachen, including its famed cathedral, was heavily damaged by Allied bombing attacks and artillery fire, but the cathedral's basic structure survived. Many of the cathedral's artistic objects had been removed to secure storage during the war, and some which could not be moved were protected within the church itself. However, the glazing of the 14th-century choir hall, the Neo-Gothic altar, a large part of the cloister, and the Holiness Chapel (Heiligtumskapelle) were irretrievably destroyed. Reconstruction and restoration took place intermittently over more than 30 years, and cost an estimated 40 million euros. In 1978, Aachen Cathedral was one of the first 12 items to be listed on the UNESCO list of world heritage sites.