The Château des ducs de Bretagne is a large castle located in the city of Nantes in the Loire-Atlantique département of France; it served as the centre of the historical province of Brittany until its separation in 1941. It is located on the right bank of the Loire, which formerly fed its ditches. It was the residence of the Dukes of Brittany between the 13th and 16th centuries, subsequently becoming the Breton residence of the French Monarchy.
The castle has been listed as a monument historique by the French Ministry of Culture since 1862. Today the castle houses the Nantes History Museum.