I came across La Bocca della Veritá (Italian for The Mouth of Truth) in Rome. It is remembered as the world's first lie detector. It is part of the exterior of the church Chiesa di Santa Maria in Cosmedin, and used to be an ancient drain.
According to legend, if you stick your hand in the mouth while telling a lie, it will be bitten off. In order to perpetuate the myth, it is said that priests used to place scorpions inside. A famous scene in the movie world where that happens can be found in Roman Holiday starring Gregory Peck and Audrey Hepburn.