To the east of the Communication channel (1) is a Christian basilica with three naves, installed in older buildings around 350 AD. The first "excavations" were ordered by the Torlonia family. The finds were given to the Lateran Museum. New excavations took place at the end of the 20th and in the early 21st century.
In the 19th century the church was identified as the Xenodochium of Pammachius, a guest-house for pilgrims, donated by the senator Pammachius in 398 AD. According to Février the basilica may have been dedicated to Peter and Paul, whose church is mentioned in 1018 AD. To the west of the building is a paved street. The church consists of a wide nave with an apse and two aisles, separated by colonnades. In the left aisle is a baptistery. In front is a square (atrium) with a quadriporticus of reused columns. The church received donations from bishop Stephanus c. 800 AD. It was enlarged and embellished in later centuries, but abandoned in the thirteenth century.
In the center of the atrium stood a square basin with an inscription on all four sides. Three sides have been preserved:
ATRIVM CVM QVADRIPORTICVM SED
[et] COLVMNAS CVM [cisterna?]
[qu]ISQ(ue) SITIT VENIAT CVPIENS (h)AVRIRE FLVE[nta]
The last line is found in Epigram 1 of Damasus (pope from 366 to 384 AD). A marble well-head with the same phrase is present in the Convent of Saint Bartholomew on the Tiber Island in Rome, to which the bishops of Portus had transferred their seat. It may well have come from this church.
The ruins of the basilica. Photograph: Jan Theo Bakker.
Plan of the basilica. Lugli-Filibeck 1935, fig. 65.