The
Unité d'Habitation in Rezé, a suburb of Nantes in western France.
Actually the building is more known under the name of its architect, Le Corbusier. It's also called
Maison Radieuse ("Shiny Happy House").
It was the second
Unité d'Habitation to be built by Le Corbusier, after the one located in Marseille (the most known). Three other ones have been built in Berlin, Briey (eastern France, near Metz) and Firminy (south-eastern France, near Saint-Etienne).
I've just bought a duplex apartment located on the two last floors !