I'm very fond of this Paris facade, on the rue du Faubourg Montmartre. It advertises hydrotherapy at the Chateaudun Baths, now long gone. There doesn't seem to be much information about what services were offered here - hydrotherapy is a general term for a whole range of therapies, popular from the mid-nineteenth century onwards, involving water. Some form of bathing seems the most likely in these Paris premises, although therapies could also involve sea water, thermal mineral springs, and so on.
If anyone has more information on this little Parisian mystery, do leave a comment!
