La Bocca della Verità ('the Mouth of Truth') is an image, carved from Pavonazzetto marble, of a man-like face, located in the portico of the church of Santa Maria in Cosmedin in Rome, Italy. The sculpture is thought to be part of a 1st century ancient Roman fountain. The most famous characteristic of the Mouth, however, is its role as a lie detector. Starting from the Middle Ages, it was believed that if one told a lie with one's hand in the mouth of the sculpture, it would be bitten off...