A bearded face carved into a giant marble disc, the Bocca della Verità is one of Rome's most popular curiosities. Legend has it that if you put your hand in the mouth and tell a lie, the Bocca will slam shut and bite it off.
The mouth, which was originally part of a fountain, or possibly an ancient manhole cover, now lives in the portico of the Chiesa di Santa Maria in Cosmedin, a handsome medieval church.
Originally built in the 8th century, the church was given a major revamp in the 12th century, when the seven-storey bell tower and portico were added and a Cosmati floor was laid.
Note that you'll usually have to wait in a lengthy line to take a photo of yourself with your hand in the Bocca. You can, however, see it from outside the portico's railings.