The catacomb, dating back to IV-V century, houses around 500 tombs and consists of three Christian cemetery galleries. The story goes that during the persecution of Diocletian, towards 304, the priest and the elder Abbondio and the deacon Abbondanzio were captured, tortured and sentenced to death by the Romans. On the way to execution, on the Via Flaminia, they met the senator Marciano and his son John, who asked to be baptized. All were decapitated and the matron Theodora collected the remains and laid thim in the cemetery where the inscription was discovered. During the reign of Otto III, in 1001, the bodies of Theodora, Abbondio and Abbondanzio were transferred to Rome.