The walled upper town of St-Valéry sits on a low chalk bluff above the bay, and the medieval ramparts that wrap it are the town's defining feature. Two fortified gates survive: the Porte Guillaume to the west, with its squat round towers, and the Porte de Nevers to the east, leading from the lower town up into the old quarter. A walk around the ramparts takes maybe twenty minutes and gives you views across the estuary as well as a sense of how the town's history sits in layers — Viking raids, English sieges during the Hundred Years' War, and the long centuries of slow decline that left so much of the medieval fabric intact.
Inside the walls, the streets are cobbled and narrow, lined with half-timbered houses and old fishermen's cottages painted in pale blues and yellows. The whole upper town is small enough to wander without a map. Aim for early evening when the light catches the brick and stone, and the tourists who have come for the day have gone back to their hotels in the bigger resorts.