Though no longer on the waterfront, the Château des Ducs still preserves the form in which it was built by two of the last rulers of independent Brittany, François II, and his daughter Duchess Anne, born here in 1477. The list of famous people who have been guests or prisoners, defenders or belligerents, of the castle includes Gilles de Rais (Bluebeard), publicly executed in 1440; Machiavelli, in 1498; John Knox as a galley-slave in 1547–49; and Bonnie Prince Charlie preparing for Culloden in 1745. In addition, the Edict of Nantes was signed here in 1598 by Henri IV, ending the Wars of Religion by granting a degree of toleration to the Protestants. It had far more crucial consequences when it was revoked, by Louis XIV, in 1685.
The stout ramparts of the château remain pretty much intact, and most of the encircling moat is filled with water, surrounded by well-tended lawns that make a popular spot for lunchtime picnics. Visitors can pass through the walls, and also stroll atop them for fine views over the city, for no charge.
The incongruous potpourri of buildings that encircle the courtyard within include the Musée d’Histoire de Nantes, where highlights include a fascinating scale model of the city in the thirteenth century, and a determined attempt to come to terms with Nantes’ slave-trading past, with its display of pitiful trinkets used to buy slaves in Africa.