Nantes is the capital of the north-western French region of Pays de la Loire. That said, Nantes has strong historical connections with the adjoining region of Brittany, and is the historical capital of the region (though not its official capital since the days of Napoleon).
With Saint-Nazaire, a seaport on the Loire estuary, Nantes forms the main north-western French metropolis. It is the administrative seat of the Loire-Atlantique department and the Pays de la Loire région, one of 18 regions of France. Nantes belongs historically and culturally to Brittany, a former duchy and province, and its omission from the modern administrative region of Brittany is controversial. Nantes was identified during classical antiquity as a port on the Loire. It was the seat of a bishopric at the end of the Roman era before it was conquered by the Bretons in 851. Although Nantes was the primary residence of the 15th-century dukes of Brittany, Rennes became the provincial capital after the 1532 union of Brittany and France. During the 17th century, after the establishment of the French colonial empire, Nantes gradually became the largest port in France and was responsible for nearly half of the 18th-century French Atlantic slave trade.