Bath Abbey stands on a religious site which dates back well before the medieval period. A monastic house for nuns was built in 676 who were replaced by monks in around 758. The abbey was possibly destroyed by invading Danes. At the time of William Rufus, in 1088, Benedictine monks took over the site and a Norman Cathedral was built by Bishop John de Villula (John of Tours). The nave of the Cathedral would have been longer than the complete length of the abbey as it stands now. The Bishop's See was moved to Bath in around 1091 due to the importance of the town and its springs. A fire in 1137 badly damaged the Cathedral. A conflict arose between the regular clergy at Bath and the secular clergy at Wells as to who should have the Bishop's seat. The conflict was resolved in 1245 when it was decided that the bishop should be called the Bishop of Bath and Wells and should be elected by both the monks at Bath and the canons at Wells. The monks were badly affected by the Black Death in 1348 when more than half of their number perished. Construction of a new church was begun in 1499, much smaller than before fitting into the area of the nave of the older building.