The narrowest house in Paris

We found the narrowest house in Paris, at just over one metre wide.  It's just wide enough for a front door (the black one) on the street, and goes up three floors, squeezed between its neighbours.  They managed to fit two windows in on each floor - I think it must be tapered, and wider out the back than it is in front.  Otherwise I don't see how they would get stairs up!

It's in Rue Saint-Severin, beside the ancient church of the same name.