It's hardly a coincidence that the word "muse" appears in "museum!" Musée Dobrée aims to educate and inspire its visitors, so add it to your itinerary.
You'll find this museum in Nantes Centre. Once you've done everything you can at Musée Dobrée, take a look at nearby Zenith de Nantes, Chateau of the Dukes of Brittany, and Nantes Cathedral.