It is composed of several groups of cemeteries of different periods from the first century to the fourth. These groups are so united by corridors that they may be considered as one vast catacomb. The Cemetery of Callistus in part dates from the first century, but it only obtained the designation of “Callistus” in the last years of the second or in the first years of the third century, when Callistus the deacon was appointed by Zephyrinus the Bishop of Rome as superintendent of The Cemetery. Subsequently Callistus succeeded Zephyrinus as bishop, and greatly enlarged the original area, one chamber of which he set apart as the official burying-place of the bishops or popes of Rome. Before the time of Callistus the official burying-place of the bishops was the cemetery on the Vatican Hill, immediately contiguous to the sepulchre of S. Peter. At the end of the second century the limited space on the Vatican Hill was completely occupied—hence the necessity for arranging a new papal crypt.

The oldest portion of the “Callistus” group is the so-called Crypt of Lucina (first and second century). It was evidently in the first instance excavated in the property of the noble family of the Cæcilii, and was used as the burying-place of Christian members of that great House. De Rossi believes that the “Lucina” in whose land the crypt was originally arranged was no other than the well-known Pomponia Græcina, wife of Plautius, the famous general in the days of Nero, whose conversion to Christianity about the year of grace 58 is alluded to in scarcely veiled language by Tacitus. If this be the case, the name “Lucina” was assumed by the great lady in question, and by which she was generally known in Christian circles. The assuming of such an “agnomen” was not uncommon among Roman ladies. The original area of the Cemetery of Lucina was greatly enlarged in the days of the Emperor Marcus and in the last years of the second century. The chapel of the popes, above alluded to, and other important funereal chambers, are included in this enlarged area.

It was in the course of the third century, no doubt after the construction of the new crypt or chapel of the popes[126] by Callistus, and of course in part owing to the presence of this great historical centre, that the cemetery assumed its grandiose proportions.

The Cemetery of S. Soteris, a vast catacomb, communicates with the older portion of the Callistus crypt and corridors. Much is as yet unexplored here. S. Soteris—virgin and martyr—who has given her name to this great cemetery, was buried “in Cemeterio suo,” A.D. 304. She suffered when the persecution of Diocletian was raging.

What we have termed the group, included generally under the term of the Callistus Catacomb, is the largest and most extensive of the catacombs which lie on the great roads which run through the suburbs and immediate neighbourhood of Rome.

The discovery of this important area of the ancient Christian City of the Dead was made in the year 1849, when De Rossi found in an old vineyard bordering on the Via Appia a fragment of an inscription bearing the letters “NELIUS Martyr.” The Itineraries had recorded that Cornelius, Bishop of Rome and Martyr, had been buried in the “Callistus” Cemetery. In the course of subsequent searches the other portion of the broken tablet was found, which completed the inscription “Cornelius Martyr.” The vineyard was purchased by Pope Pius IX, and very soon the searchers came upon the ruined chapel of the popes and the crypt of S. Cecilia.

The position of the historic Callistus Catacomb was thus established beyond doubt, and for some fifty years portions of the great cemetery have been slowly excavated by De Rossi and his companions; the results have been of the highest importance, and have contributed in no little degree to our knowledge of early Christianity—its faith—its hopes—its anticipations.

The Cemetery of Prætextatus is on the left hand of the Via Appia, almost parallel with the usual entrance to the vast network of the Catacomb of Callistus. It is, comparatively speaking, a cemetery of small dimensions, but of great antiquity. It must have been arranged quite early in the second century; not improbably portions of this cemetery date from the first century. Some of the decorations of the historic crypt are elaborate and striking, and evidently belong to the best period of classical art. As yet it has only partially been explored. It runs under private property, and the owner apparently is unwilling to allow a detailed examination: this is disappointing, as owing to its great antiquity and possessing some historic crypts, once the resting-places of famous heroes in the early Christian combat, probably discoveries of high interest would result from a prolonged and careful search.

As early as A.D. 1857 De Rossi discovered in this cemetery of Prætextatus some crypts highly decorated, evidently the resting-places of certain famous martyrs referred to in the Pilgrim Itineraries as sleeping in this catacomb.

There are many indications that we meet with here which tell us that this is a very ancient cemetery. Speaking of this catacomb of Prætextatus, the pilgrim itineraries mention particularly three of those small Basilicas in the immediate vicinity, which frequently in the fourth or fifth centuries were built directly over the crypt or crypts which contained the remains of well-known martyrs and confessors; this was for the convenience of pilgrims who came after from distant countries to pray at the shrines: the ruins of two of these Basilicas, apparently dedicated to SS. Valerian, Tiburtius, Maximus, and Zeno, have been discovered here. Of these confessors, Valerian and Tiburtius were respectively the husband and brother-in-law of S. Cecilia. Zeno[127] was also a martyr. Maximus was the Roman officer who had charge of the execution of Valerian and Tiburtius, and who, seeing their constancy under torture, became a Christian, and was in consequence put to death.