It was the maritime environment of Mont-Tombe that prompted the settlement of a few early medieval monks. It was also decisive when, in 708, after three successive apparitions of Saint Michael, Bishop Aubert of Avranches decided to found a sanctuary there dedicated to the archangel. Over the centuries, the Benedictine monks built one of the most extraordinary examples of medieval religious architecture. Overlooking the immensity of the bay, the abbey is the crowning jewel. The Mont-Saint-Michel and its bay have been listed as a UNESCO World Heritage Site since 1979.