PETRONIUS, Saint. — The information concerning him is uncertain and obscure. In the *Roman Martyrology* he is commemorated on October 4.
From the few references given by Gennadius, it can be inferred that he was Bishop of Bologna, that he wrote a series of *Vitae Patrum*, and that he died before 450. A biography of P. was written toward the end of the 12th century, based on oral traditions and filled with fables. According to this account, P. was born in Constantinople, of an illustrious family descended from Constantine the Great; as a youth he studied in his native city, making great progress in science and piety; he won the esteem of the clergy and, through his brother-in-law, Emperor Theodosius II, obtained several court positions. Sent to Rome to report to Pope Celestine on certain heretics, he was elected Bishop of Bologna. There he worked to build churches, reproducing the holy places of Jerusalem, and after his death he was buried in the church of St. Stephen, which he had built.