Saint-Nazaire has a long history of human occupation dating back to Neolithic times. Archaeological evidence from the Roman era suggests the medieval church was built on the site of an ancient settlement. The village grew in importance due to its location along a major Roman road. By the 13th century, the village was well established within a developed agricultural landscape. The village fort was constructed in the late 14th century for defensive purposes. Over subsequent centuries, the population fluctuated in response to wars, plagues, and economic changes. By the mid-20th century, the population had tripled to 900 due to industrial development in the region.