You can visit the outside of the château free of charge every day from 10am to 7pm: we recommend a tour of the ramparts for an uninterrupted view of the city, followed by a visit to the Nantes History Museum if you have more time.
Inside the château, the Musée d'Histoire de Nantes and the exhibitions: Every day except Monday, from 10am to 6pm.
The museum's collections tell the story of the city of Nantes by theme: Brittany, The World Wars, The Loire, Biscuit factories, etc.
Here's a practical tip: you can download the Nantes Musée app free of charge to accompany your visit to the 32 rooms.
Download links on the Château Musée website.