Saint-Nazaire is a commune in the Loire-Atlantique department in western France, in traditional Brittany.
The town has a major harbour, on the right bank of the Loire River estuary, near the Atlantic Ocean. The town is at the south of the second-largest swamp in France, called «la Brière». Given its location, Saint-Nazaire has a long tradition of fishing and shipbuilding.
Archaeologists believe that Saint-Nazaire is built upon the remnants of Corbilo, an Armorican Gaulish city populated by the Namnetes tribe, which (according to the Greek navigator Pytheas) was the second-largest Gaulish city, after Massilia (now Marseille). Archeology suggests that the area has been inhabited since at least the Neolithic period, as evidenced by the presence of monuments like the tumulus of Dissignac and the dolmen located in the centre of the present-day city, and ancient bronzes found in the vicinity.
According to the 15th-century chronicler Alain Bouchart, Brutus of Troy, the mythical ancestor of the Bretons, travelled toward Saint-Nazaire to set foot upon the new homeland of his people. Historical accounts note that at the end of the Roman Empire, some Britons colonized the Loire estuary, and later, the peninsula containing Guérande. The furthest extent of the ancient Breton language in the Loire region is Donges, to the east of Saint-Nazaire.