Notre-Dame de Bon-Port is a 19th-century basilica near the Quai de la Fosse, close to Nantes' old port world. Its dome deliberately echoes Les Invalides in Paris, while the church's harbour dedication fits a city whose wealth and troubles were long tied to the Loire and Atlantic trade.
It is not Nantes' most essential sight, but it is a worthwhile architectural stop if you are walking between the centre, the riverfront, and the Jules Verne side of town. Step inside if the doors are open; the scale and light are more interesting than the restrained exterior first suggests.