Nantes is approximately 220 mi/355 km southwest of Paris, or about a two-hour ride on the TGV, the high-speed train. It's a beautiful city and merits at least an overnight visit.
Notable sights include numerous 18th-century monuments, the Castle of the Dukes of Brittany, the Chateau de Goul and the fine-arts museum. This is the birthplace of Jules Verne, and there is, of course, a museum dedicated to his work and ideas.
In the evening, you can dine aboard boats that take you down the River Erdre, past beautifully lit chateaus.
