Few places on Earth give a better view into medieval life than Mont Saint-Michel. Built on a rocky outcropping situated in the midst of a tidal floodplain, standing among the fortifications visitors can look out across salt marshes filled with grazing sheep and get a view similar to that of the 10th and 11th centuries. During high tide, the monastery and buildings within Mont Saint-Michel’s walls become an island with impressive defenses. The island famously resisted an attack by the English with only a small garrison in the 15th century and remained unconquered during the Hundred Years’ War. This was of immense importance, given the island’s position along the relatively flat coastal plains of Normandy, a favorite invasion route of would-be attackers for hundreds of years. Mont Saint-Michel’s existence is owed to the difficulties France has faced in securing Normandy’s coastline, the furthest western extension of the Northern European Plain that saw nearly constant fighting among residents until the peace imposed by the United States under the Bretton Woods system.