Mouth of Truth in Rome, Italy

Made famous by Audrey Hepburn and Gregory Peck in Roman Holiday, La Bocca della Verità is perhaps the only former manhole cover in the world that acts as a polygraph test.
Standing outside the church of Santa Maria in Cosmedin near the Ponte Palatino in Rome, Italy, it supposedly catches out liars.
The old manhole cover takes the form of a human face carved into stone, and it has a small stone hole in which the brave can put their hand, and then make a statement. Should your words be the truth, you will be able to pull your hand out with no effect.
Should you tell a dastardly, wicked lie – and now is probably not the time to continue your line about how the hamster died or how much that bargain pair of shoes cost – the mouth will snap shut and bite your hand off. There must be a lot of honest people around, as there is no pile of amputated fingers to be seen on the floor beneath.