Around 507, the Celtic hermit Aaron was seduced by this inhospitable rock, almost an island at high tide. His faith in God attracted young solitaries with whom he founded a community to evangelise the area and build a monastery. The most famous of his companions was the Welsh monk Maclow, later known as Saint Malo. In 552, Malo succeeded Aaron and became the first bishop of Alet, the nearby Gallo-Roman city founded in the 1st century BC on a peninsula. Around 1100, the inhabitants of Alet migrated to the rock of Saint-Malo and founded a city surrounded by ramparts around the cathedral of Saint-Vincent.