The Mouth of Truth in Rome: what it is and where the legend comes from

There's usually a queue at the portico to put a hand in that stone mouth. Some grin, some pull their hand out sharpish, and nearly everyone takes a photo.

What is the Mouth of Truth?

It's a marble disc about 1.80 metres across. The basilica that looks after it reckons it weighs around 1,300 kilos. It's carved with a bearded man's face, and the eyes, nose and mouth are pierced.

Who is he meant to be? Nobody knows for sure. Suggestions include Jupiter, a faun or a river god, and the basilica itself puts forward other readings we haven't been able to check. As for what it was originally for, Rome's official tourism website and a nineteenth-century scholar agree on the most likely answer: it covered a drain, a Roman sewer opening.

So, to put it bluntly: anyone who puts their hand in there is, in all probability, putting it into what used to be a drain cover. A very old and very famous one, mind you.

Where is it, and since when?

It's on Piazza della Bocca della Verità, inside the portico of Santa Maria in Cosmedin. But it hasn't always been indoors. For centuries it leant against the church's outside wall. In 1632 a canon named Placidi had it moved into the portico, where it's been ever since.

Why do people put their hand in it?

Because of the legend. The classic version says that in the Middle Ages anyone who had to swear an oath would slip their hand between those stone lips, and if they swore falsely, the mouth would bite. The name certainly suits it: a mouth that can tell truth from lies.

Over time the legend picked up more stories. Rome's tourism website mentions one: "The tradition was widespread among jealous husbands, who brought their wives to the monument", so that they'd swear to be faithful with a hand inside.

The basilica tells another one, complete with a loophole. A young nobleman suspects his wife is cheating on him and takes her to the mouth. She's nobody's fool, and hatches a plan with her lover: when the test comes, he'll pretend to have lost his mind and hug her in front of everyone. The moment arrives, the fake madman plays his part, and she puts her hand in and swears that no man has ever embraced her except her husband and that poor lunatic. Her hand comes out without a scratch. She hadn't told a single lie. She'd just arranged the truth very carefully.

The basilica tells it for what it is, a legend, and we haven't found its earliest written version. But it sums up the character nicely: a stern mouth that, it seems, could be outwitted with a little cunning.

Is it really a medieval legend?

Here's a detail you don't often hear. The oldest text we've read about the medieval oath comes from Mariano Armellini, who in 1891 published a great survey of Rome's churches. He introduces it with "it used to be said", without citing a single medieval document. So we know that by the end of the nineteenth century the legend was taken to be medieval. The medieval document that would prove it, we haven't seen.

What Armellini does describe from his own day is something else, and it's lovely: Roman mothers, he writes, still made their small children put their hands in the hole, and the little ones did it in terror, or at the very least with deep suspicion. The mouth no longer passed judgement on anyone, but it still worked as a test of nerve.

And the famous medieval guidebook? Plenty of websites claim the Mouth of Truth appears in the Mirabilia Urbis Romae, "The Marvels of the City of Rome", a guide for visitors written in the twelfth century.

We went and checked the text. The passage people usually quote is about a statue, a simulacrum, that spoke to the Emperor Julian and deceived him. But it sits in the section on the Esquiline, next to Santa Maria in Fontana and a temple of Faunus: on a different hill of Rome, a long way from Santa Maria in Cosmedin. That text gives no grounds for identifying the statue with the Mouth of Truth.

What has "Roman Holiday" got to do with it?

Quite a lot. For centuries the mouth was a Roman curiosity with a local legend attached. What turned it into a worldwide icon was the cinema: Roman Holiday, directed by William Wyler and released in 1953. A princess, played by Audrey Hepburn, slips away from her embassy and explores the city with a journalist, played by Gregory Peck. They pass the Trevi Fountain and the Spanish Steps, ride a Vespa… and end up at this mouth, where both of them put a hand inside.

Since then, putting your hand in the Mouth of Truth hasn't been an oath or a test for frightened children. It's re-enacting a scene from a film.

Look at the whole chain: a Roman drain cover, a stone propped against a wall for centuries, a legend about oaths that a nineteenth-century scholar describes as medieval, mothers using it to test their children's courage, and a Hollywood film. Every age has asked something different of it. And it's put up with all of them, bearded face and open mouth.

Fact or legend.

• Fact: it's a marble disc about 1.80 metres across with a pierced, bearded face; its most likely original use was as a Roman drain cover; it stood against the church's outside wall for centuries and was moved into the portico in 1632; Roman Holiday (1953) made it world-famous.
• Legend: that it bites anyone who swears falsely. It's been called medieval since the nineteenth century, with no medieval document to prove it. The jealous husbands and the wife with the fake madman are legends too.
• False: that the medieval Mirabilia guide mentions it. The passage usually quoted is about a different hill, and we haven't found it anywhere else in the guide.
• Unconfirmed: who the face represents. And the year 1485, which circulates as the first mention of the name "Bocca della Verità": Rome's tourism website gives it without saying where it comes from, and we haven't been able to verify it.

Where to hear it

The Mouth of Truth is the last stop, "The mouth said to bite", on "Legends from the Capitoline to the Mouth of Truth", a Podtour route that heads down from the Capitoline through Rome's oldest legends, each with whatever truth it holds. There, the mouth rounds off the walk and pairs up with another legendary stone along the way, the Tarpeian Rock, the traitors' rock.

And if you're left wanting more Roman Holiday, the route "Piazza del Popolo and Via Margutta" has a stop, "Joe Bradley's apartment", outside the doorway at Via Margutta 51, where the film puts the journalist's flat.

If you're planning your trip, our Rome guide has the practical side covered.

Further reading

• Mariano Armellini, Le chiese di Roma dal secolo IV al XIX, "Rione Ripa", Tipografia Vaticana, 1891; transcribed by Bill Thayer on LacusCurtius (in Italian). https://penelope.uchicago.edu/Thayer/I/Gazetteer/Places/Europe/Italy/Lazio/Roma/Rome/churches/_Texts/Armellini/ARMCHI*/2/Ripa.html
• Roma Capitale, Turismo Roma, "The Mouth of Truth". https://www.turismoroma.it/en/places/mouth-truth
• Basilica di Santa Maria in Cosmedin, "La Bocca della Verità" (in Italian). https://cosmedin.org/la-bocca-della-verita/
• Anonymous, Mirabilia Urbis Romae, §29, "De Exquilino monte" (twelfth century), on The Latin Library (in Latin). https://www.thelatinlibrary.com/mirabilia.html
• Italy for Movies (portal of the Italian film commissions), "Vacanze romane". https://www.italyformovies.it/film-serie-tv-games/detail/6590/vacanze-romane