Faux painting is not at all uncommon in Italy; even our La Lombarda has one faux window painted on to even out a wall. Stones are painted on for effect, molding details, etc. Here, the faux effect is made more complete by the addition of the real stone window sills and the shutter holders on the wall. But the cat and bird are pure whimsy. 

Take a good look around you at buildings; is everything you're seeing really there?