People come to this little church (indeed, stand on line) not for great art treasures, but to see the “Mouth of Truth,” a large disk under the portico. It is no longer possible to pull a “Gregory Peck” and actually put your hand in the mouth, like the star did, demonstrating to Audrey Hepburn in the film “Roman Holiday” that the mouth is supposed to chomp down on the hands of liars. The purpose of this disk—which is not of particular artistic interest—is unclear. One hypothesis says that it was one of many Roman “talking statues.” If you wanted to rat someone out, you could slip an anonymous note inside the open mouth.
As for the church, it was first erected in the 6th century but was subsequently rebuilt. A Romanesque bell tower was added at the end of the 11th century.