 The mention in a letter of Pope Gregory the Great of a John newly elected as bishop of Bagnoregio is the earliest extant mention of a bishop of the see of Bagnoregio, but he was doubtlessly not the first bishop.The diocese grew over the centuries, incorporating in 1015 what had been the diocese of Bomarzo.After an earthquake in 1695, the cathedral that had been in Civita di Bagnoregio was replaced by one at Bagnoregio itself.