This polygonal building protects the most vulnerable part of the ramparts. Spread over four floors, the tour shows a diversity of collections while displaying the castle interior: there are Greek and Egyptian collections including a lovely selection of vases, French and foreign earthenware, paintings from the Opale coast (Boudin, Corot), sculptures (Carpeaux, Pompon), and ethnography exhibitions including eskimo and Aleut masks, and those from the Middle Ages and Renaissance.