St. John the Baptistery is the oldest Christian monument in France. Indeed, it has been built around the year 360, probably on the order of Saint-Hilaire, first bishop of Poitiers, before being rebuilt in the seventh century. The curiosity of the most remarkable of the first period is undoubtedly the octagonal pool, fed by an aqueduct and then used for baptism by immersion. During the visit of the Baptistery, one can also admire the murals, the oldest of which date from the eleventh century. The Baptistery has a small archaeological museum Merovingian.