Quite recent investigation and discoveries have now satisfied Marucchi, the last explorer and student of the catacombs, long the assistant and disciple of De Rossi, that the Cemetery of Priscilla must be identified as the locality of the preaching and teaching of S. Peter--so often alluded to as the “Sedes ubi prius sedit sanctus Petrus”--that the Cemetery of S. Priscilla was the “_Cœmeterium ad Nymphas beati Petri ubi baptizaverat_.” Marucchi has with infinite pains and scholarship proved his point, and has shown to a wondering group of interested scholars the very pools still filled with water in the dark crypts of S. Priscilla in which the great apostle probably baptized the first converts to the religion of his Master, for whom in the end he witnessed his noble confession on the Vatican Hill in the reign of the Emperor Nero. The Cemetery of Priscilla, as at present explored, consists roughly of two vast galleries; many of its crypts and corridors dating from the first and second centuries. Their age is accurately determined, among other well-known signs, by the character of the decorative work and by the nature and phraseology of the inscriptions; the existence of the many _Greek_ epitaphs is one other sure proof of the very early date of the interments. From the notices in the Pilgrim Itineraries, notwithstanding their present often ruined and desolate condition, a good many of the original tombs of the more famous confessors and saints can be fairly identified. We will indicate a few of the more remarkable features of this important and venerable cemetery.