According to the legend, after being decapitated, the head of the apostle Paul jumped three times, and is symbolically represented by three fountains (hence the name of the abbey). The abbey comprises three churches that were built on the place of his martyrdom. The church of SS. Vincenzo e Anastasio, founded by Onorio (625) and rebuilt by Onorio III (1221), is the biggest one of the three. It is entirely made of bricks and presents a high façade with double sloping and a high and spacious porch with Ionic columns and capitals.The church of Santa Maria Scala Coeli is located on the place where, according to tradition, over ten thousand christian legionnaires supposedly endured martyrdom by the hand of Diocleziano. It consists of a little temple with side chapels and apse. It was built by Giacomo Della Porta (1582).The San Paolo alle Tre Fontane church dates back to C.V but was completely modified by Giacomo Della Porta in1599. The interior includes the three fountains miracolously gushed out and, on the pavement, a polychrome Roman mosaic with the four seasons (coming from Ostia). The area nearby the abbey was once known as "Acque Salvie" and for a long span of time it remained desert being considered malarial area. In 1868 the Trappist monks planted a wood of eucaliptii out of which a famous liqueur is still distilled nowadays. Great attention should be given to the Grotta delle Tre Fontane, nowadays a sanctuary highly attended by pilgrims, where the Virgin appeared on the 12th of April 1947.