Obviously I missed this interesting sight in Paris.
Luckily later I got to know about this sight as well as work from someone I know. It is a short story “Le Passe-muraille” Marcel Aymé wrote in 1943, which is translated as “The Man Who Walked through Walls.” I found a free on-line copy (see here) translated by Karen Reshkin.
Interesting little black-humor piece.
Herumreisende 