Mouth of Truth

The Bocca della Verita is a massive marble disc, about one point eight metres in diameter, depicting a river god or possibly Oceanus, with an open mouth that legend says will bite the hand off anyone who tells a lie while their fingers are inside. In reality, it is almost certainly a Roman manhole cover — a drain cover for the Cloaca Maxima, the great sewer of ancient Rome that emptied into the Tiber nearby. So the most famous lie detector in the world is a sewer lid. Rome in a nutshell.

The lie-detector legend dates to at least the Middle Ages. One popular medieval version involves a woman accused of adultery who was ordered to put her hand in the mouth to prove her innocence. She arranged for her lover to disguise himself as a madman and kiss her publicly before the test, then swore she had only ever been kissed by her husband and that madman — technically true. The mouth did not bite. The legend's real value was social: in a world without forensic science, the fear of the Bocca was enough to make people confess.

Gregory Peck and Audrey Hepburn made this spot iconic in the 1953 film Roman Holiday. In the scene, Peck pretends the mouth has bitten his hand off, and Hepburn screams. The moment was improvised — Peck did not tell Hepburn he was going to do it, and her reaction is genuine. That single unscripted moment turned a little-known Roman curiosity into one of the most visited spots in the city.

The disc sits in the portico of the Basilica of Santa Maria in Cosmedin, a beautiful twelfth-century church that almost nobody enters because the queue for the mouth extends past the door. The church has a stunning Cosmatesque floor and a medieval crypt, and it is worth ducking inside after your photo. There is usually a long line, but it moves quickly — everyone just sticks their hand in, snaps a photo, and moves on.