Modern Art Museum in Saint-Étienne Métropole. There are 2 stamps on the back showing a woman's face with stars. I didn't know who she was so I looked it up and it turns out she is Marianne and has been used on most French definitive stamps since 1944. I also found this information:
Marianne is a symbol of Republican France. A Marianne is a bust of a proud and determined woman wearing a Phrygian cap. She symbolises the attachment of the common citizens of the revolution to the Republic - Marianne is liberty, egality and fraternity.
I love postcrossing not only for the postcards but for the education! It's always nice to learn new things. The postcard took 29 days to get here and traveled a distance of 4,304 km.