Tourists exploring nearby Campo de Fiori are often completely unaware of the existence of a hidden passageway connecting the Piazza del Biscione with via di Grottapinta.

Passetto del Biscione is tiny alley with a remarkable story. It was most likely named most likely after the eel, the heraldic symbol of the Orsini family who built their palace over the ruins of the Theatre of Pompey, Rome's first theater. If you look carefully, you can trace the theater’s shape by observing the sequence of the buildings on the road.

In 1796, an image of the Madonna within the alley was purportedly seen moving its eyes, a miracle that drew pious Christians from all over the city. But the effigy’s hidden location complicated the quest to witness the miracle. It inspired the expression "andare a cercare Maria per Roma" (“to look for Mary around Rome”) to indicate something that is remarkably hard to find yet very near.

After decades of abandonment, the alley was restored to its present beauty by a team financed by the Orsini Chapel Study Centre. Its beautiful frescoes with cherubs and festoons have been painted according to surviving illustrations and drawings. A copy of the painting of the Madonna still attracts devotion from passersby.