The square is located in the old area of the Forum Boarium, right in front of the Tiber Island, and it owes its name to the Mouth of Truth (Bocca Della Verità), which today is in the portico of the Church of Santa Maria in Cosmedin.

Apart from the church, which belongs to the late period of the Middle Ages, you can also find the Arcus Argentariorum, the Arch of Janus, the Temple of Hercules and the Temple of Portunus in this square.

The fountain in front of the two temples, called the Fountain of the Tritons, was put in the square in 1715.

Capital executions were performed in this square until 1868.