The Basilica of Santa Maria in Cosmedin, one of the most visited sites in Rome, stands in the ancient area of the Forum Boarium, on the site of the Ara Maxima of Hercules, one of the most important sanctuaries of archaic Rome.

The earliest records of the church date back to the 6th century, when it was known as Sancta Maria in Schola Graeca and served as a diaconia, a charitable and administrative centre of the early Roman Church. In 782, Pope Adrian I commissioned a major enlargement, incorporating the area of the ancient Ara Maxima and adapting it to the needs of the Christian community.

A few years earlier, or around the same period, the church had become closely associated with the large Greek and Byzantine Greek community living in the area. This community also included religious figures and refugees who had arrived in Rome following the iconoclastic controversies and persecutions that affected the Byzantine East. The bank of the Tiber at the foot of the Aventine became known as Ripa Graeca, while the surrounding area was called Schola Graeca, reflecting the presence of a particularly active Greek community.

The name Cosmedin is also connected with this Greek presence. It derives from the Greek Kosmidion, meaning “ornamented” or “decorated”, and is associated with the ancient monastery of the same name in Constantinople, to which the Greek community connected with the church referred.

The basilica still preserves important evidence of the different periods of its history. The interior, largely restored to its medieval appearance, is divided into three naves by ancient columns and pillars. Its Cosmatesque pavement, schola cantorum, fragments of medieval frescoes and Gothic ciborium make it one of the most evocative medieval interiors in Rome.

But the reason for the basilica’s worldwide fame, and the feature that attracts thousands of visitors who patiently queue for a photograph, is undoubtedly the Mouth of Truth: a huge circular marble mask, approximately 1.8 metres in diameter, now set into the portico of the church.

Its original function is uncertain. The most widely accepted interpretation identifies it as an ancient cover or drainage element belonging to a Roman sewer or water-management system. The face, with its pierced eyes, nose and mouth, has variously been interpreted as a river deity, a faun or another figure connected with Roman religious imagery.

Its fame, however, is above all linked to the legend that the Mouth of Truth could detect lies: anyone who made a false statement while placing a hand inside its mouth supposedly risked having the hand bitten off.

For centuries the marble mask stood outside the basilica. It was moved into the portico of Santa Maria in Cosmedin in 1632, where it remains today.

Ripa Graeca

Among the myths and legends associated with the Mouth of Truth, perhaps the most entertaining is the story of the unfaithful wife of an important Roman, who was subjected by her husband to the famous test of the hand.

Aware of her guilt, the woman devised an ingenious way to escape punishment. On the day of the trial, as she approached the Mouth of Truth, a young man suddenly broke away from the crowd and passionately embraced her.

His behaviour was so inappropriate that he was considered insane and was therefore led away without further consequences. The woman was then able to continue with the test. She solemnly placed her hand inside the Mouth of Truth and declared that she had never been touched by any man other than her husband, making only one brief exception for the “poor madman” who had just embraced her.

According to the legend, the supposed madman was, of course, actually her lover. In this way, the woman managed to make a statement that was technically true and saved her hand, proving that even the most fearsome lie detector can be outwitted with a clever play on words.

The story is one of the best-known legends associated with the Mouth of Truth and forms part of the long tradition of stories surrounding this extraordinary Roman monument.