The martyrdom in Rome rests on early testimony, beginning with the Letter of Clement. The link with this site is documented only from about the seventh century, and the story of the three springs is later than the martyrdom by centuries. Benedict XVI traced the account that Paul's head bounced three times, with a spring rising each time, to a fifth-century text and called it the most legendary of the later accounts. The springs are marked by three shrines inside the church, and their water has been closed off since 1950. A column fragment shown as the one on which he laid his head is also a late tradition.
The abbey is at Via Acque Salvie 1. Besides San Paolo there are two other churches: the abbey church of Sts. Vincent and Anastasius, open from early morning until evening, and Santa Maria Scala Coeli, open from mid-morning until mid-afternoon. The listing mentions no admission charge. The monks' shop is open Monday to Saturday from mid-morning until evening, the café Tuesday to Sunday, and Mass times are posted on the abbey's own website. The tourism office notes that hours can change and gives the abbey's telephone as +39 06 5401655.
Tre Fontane is quiet and wooded, shaded by the eucalyptus the Trappists planted in 1868, and rewards an unhurried hour. It lies about two miles (3 km) from St. Paul Outside the Walls, where the Apostle is buried, so the two fit into one half day. The city's listing gives no transit directions; check Rome's transit planner or take a taxi from St. Paul's.