The Mouth of Truth is an ancient marble mask made famous by the film 'Roman Holiday' starring Audrey Hepburn. Legend says the mouth will bite off the hand of a liar who places it inside. Located in the portico of the beautiful 8th-century Santa Maria in Cosmedin church, which features stunning Cosmati floors and medieval frescoes. Lines can be long but the photo moment is iconic. Combine with exploring the nearby Temple of Hercules and Forum Boarium.