Mont-St-Michel (St. Michael’s Mount) is a tidal island, located at the mouth of Couesnon River in Lower Normandy (France). In 8th century, St. Aubert, bishop in Avranches, founded a first chapel devoted to St. Michael. In 1067, the monastery of Mont-St-Michel supported the duke William of Nomandy (William the Conqueror) in his claim to the English throne. After 1789, the abbey was closed and converted to a prison. In 1863 the prison was finally closed and in 1874 was the mount declared as a French historic monument. Mont-St-Michel is now an UNESCO World Heritage Site (since 1979).