Philippe-Auguste Wall Tour - 2-4 rue Antoine Dubois
This is on a small side street leading up from rue de l'Ecole de Médécine to rue Monsieur le Prince!
This is a pedestrian-only street, I believe, as told to me by Michael Osman; he also states:
There's a statue between the steps we had to climb at the end of this street as we continued our walk towards the boulevard Saint-Michel.