But they have an unexpected link to one of the city's most popular tourist destinations that might not please the thousands of people who come here. The famous Bocca della Verita, the mouth of truth, has been linked since the Middle Ages to a tradition that if an unfaithful lover put his or her hand in the mouth, it would be bitten off. In Roman times, it wasn't a good idea to put your hand in that hole, whether you were faithful or not. This is in fact a monumental sewer cover, decorated with the face of Oceanus, God of the oceans. The risk was not so much from infidelity as from infection.