BASILICA OF S. PETRONILLA,
supposed to have been built about A.D. 400, was discovered, the top being only a few feet below the ground. It is supposed to have been originally built for the devotees who resorted to the tombs of the martyrs, and was destroyed by the Lombardians. On the wall of the tribune is a graffito of a priest preaching, probably S. Gregory, whose chair was removed from here to the church of SS. Nereo e Achilleo. (See [page 279].)
Beneath the floor were discovered many tombs covered over when the basilica was built. It is being restored as a monument to Monsieur Merodi.
A fresco was found representing S. Petronilla receiving Veneranda. Several inscriptions have been found; also the columns which supported the baldachino, on which are represented the martyrdoms of SS. Achilleus and Nereus.
The Romans built an altar at the springs of the river Numicius to Anna, the sister of Dido, who became the wife of the god of the river Numicius, and was called Anna Perenna. (See Ovid, "Fasti," iii. 542.) The Roman Church erected a chapel to her on the same spot, under the title of Santa Petronilla, said, without scriptural authority, to have been S. Peter's daughter, and to have died in Rome, May 30th, A.D. 98, in the reign of Domitian. This could not be the case, for Domitian died A.D. 96, and Trajan was emperor before the last of May A.D. 98, Nerva having reigned between. Straight on leads to S. Paul's outside the walls.
Returning to the Via Appia, on the right is the