A strongly fortified seaport of France, on the Brittany coast (department of Ille-et-Vilaine), at the mouth of the Ranee; the old town is built over the Rocher d'Auron, an islet connected with the mainland by a causeway 215 yards long; there is a good harbour, and a considerable amount of shipping is done; potatoes, dairy-produce, and some cereals are exported. It was the birthplace of several distinguished French authors and sailors.