Saint-Pierre-d'Oléron is the main town on the island, with a lively Saturday market in the central square that draws locals from across Île d'Oléron. The market sells Oléron oysters, island honey, goat's cheese, fresh fish, and local vegetables — it's one of the better Atlantic coast markets in the region and worth timing a visit around.
The town has an attractive main square shaded by plane trees, a covered market hall, and the unusual 12th-century lanterne des morts in the adjacent cemetery — one of the odder and more ancient monuments on the island. The tourist office here can provide cycling maps of the island's bike path network. Several good cafes and restaurants surround the main square.