Maison de la Culture Le Corbusier is 0.3 mi (0.5 km) from central Firminy, why not stop by during your stay. If you want to experience more of the culture Firminy has to offer, head to Gorges de la Loire.
If museums are on your list of things to see in Saint-Julien-d'Ance, then you might want to head to Moulin d'Ancette. If you want to experience more of the culture Saint-Julien-d'Ance has to offer, head to Bourianne Lava Flow.