Mamertine Prison

According to tradition the prison was built around 640 to 616 BC under King Ancus Marcius, on the north-eastern slope of the Capitoline Hill by the Comitium. Its lower level, the Tullianum, was originally a cistern for a spring that rises in the floor. The Romans did not use it for long sentences: prisoners were held here only briefly before their trial or execution.

Among those who passed through its cells were the Gallic leader Vercingetorix, the Numidian king Jugurtha, who died of starvation here in 104 BC, members of Catiline's conspiracy, Sejanus, the confidant of Emperor Tiberius, and the Jewish rebel leader Simon bar Giora. Christian tradition holds that Saint Peter and Saint Paul were imprisoned in the Tullianum, and that Peter used the water of the spring to baptise his fellow prisoners.

Above the prison stands the church of San Giuseppe dei Falegnami. Below it, the chapel of San Pietro in Carcere has an altar with an inverted cross recalling Peter's crucifixion. A visit takes you down into the dark stone chambers with a digital audio guide that tells their story.