When these graves were not very deep, the floor of the basilica was almost level with the ground, as in the case of S. Peter's, S. Paul's, and S. Valentine's; in other cases it was sunk so deep in the heart of the hill that only the roof and the upper tier of windows were seen above the ground, as in the basilicas of S. Lorenzo, S. Petronilla, etc. There are two or three basilicas built, or rather excavated, entirely under ground. The best specimen is that of S. Hermes on the old Via Salaria.
It soon became evident that edifices sunk in such awkward places could hardly answer their purpose, on account of dampness and the want of air and light. Several steps were taken to remedy the evil. Large portions of the hills were cut away so as to make the edifice free on one or two sides at least, and outlets for rain or spring water provided. We have a description of the system of drainage of S. Peter's, written by its originator, Pope Damasus, in a poem the original of which, discovered by Pope Paul V., in 1607, is preserved in the Grotte Vaticane:—
"The hill was abundant in springs; and the water found its way to the very graves of the saints. Pope Damasus determined to check the evil. He caused a large portion of the Vatican Hill to be cut away; and by excavating channels and boring cuniculi he drained the springs so as to make the basilica dry and also to provide it with a steady fountain of excellent water."[68]
The Acqua Damasiana is still in use, and has the honor of supplying the apartments of the Pope. Its feeding-springs are located at S. Antonino, twelve hundred yards west of S. Peter's. The aqueduct of Damasus, restored in 1649 by Innocent X., is neatly built in the old Roman style; the channel is four feet nine inches high, three feet three inches wide, and runs through the clay of the hill at a depth of ninety-eight feet. The principal fountain, in the Cortile di S. Damaso, was designed by Algardi in 1649.
Apparently the works accomplished for the same purpose at S. Lorenzo fuori le Mura, by Pope Pelagius II. (579-590), were no less important. They are described in another poem, a modern copy of which (1860) is to be seen on the side of the mosaic in the apsidal arch. The poem relates how the hill of Cyriaca was cut away, and how, in consequence of the excavation, the church became light, accessible, and free from the danger of landslips and inundations. The importance of the work of Pelagius is rather exaggerated by the composer of the poem. The church was never free from dampness and want of air and light until the pontificate of Pius IX., who cut away another section of the hill.
The damage done to the catacombs by the builders of these sunken basilicas is incalculable. Thousands of graves must have been sacrificed for the embellishment of one.
The reader cannot expect to find in these pages a description of this class of basilicas; that of S. Peter's alone would require several volumes. I have in my modest library not less than twenty-two volumes on the subject, an insignificant fraction of the Petrine literature. And what do we know about S. Peter's? Very little in comparison with the amount of knowledge that lies yet unpublished in the volumes of Grimaldi,[69] in the archives of the Vatican, in epigraphic, historical and diplomatic documents scattered among various European libraries.
The history of the building has yet to be written. Duchesne's "Liber Pontificalis" and de Rossi's second volume of the "Inscriptiones Christianæ" provide the necessary foundations for such a work. Let us hope that the Vatican will soon find its own Rohault de Fleury.[70]
The following sketch of the origin of the two leading sacred edifices of Rome may answer the scope of the present chapter. But let me repeat once again the declaration that I write about the monuments of ancient Rome from a strictly archæological point of view, avoiding questions which pertain, or are supposed to pertain, to religious controversy. For the archæologist the presence and execution of SS. Peter and Paul in Rome are facts established beyond a shadow of doubt by purely monumental evidence. There was a time when persons belonging to different creeds made it almost a case of conscience to affirm or deny a priori those facts, according to their acceptance or rejection of the tradition of any particular church. This state of feeling is a matter of the past, at least for those who have followed the progress of recent discoveries and of critical literature. However, if my readers think that I am assuming as proved what they still consider subject for discussion, I beg to refer them to some of the standard works published on this subject by writers who are above the suspicion of partiality. Such are Döllinger's "First Age of Christianity" (translated by Henry Nutcombe Oxenham, second edition, London, Allen, 1867); Bishop Lightfoot's "Apostolic Fathers," part ii., London, Macmillan, 1885, one of the most beautiful and conclusive works on early Christian history and literature; and de Rossi's "Bullettino di archeologia cristiana," for 1877. Bishop Lightfoot justly remarks that when Ignatius—the second apostolic father, a contemporary of Trajan—writes to the Romans "I do not command you, like Peter and Paul," the words are full of meaning, if we suppose him to be alluding to the personal relations of the two apostles with the Roman Church. In fact, the reason for his use of this language is the recognition of the visit to Rome of S. Peter as well as S. Paul, which is persistently maintained in early tradition; and thus it is a parallel to the joint mention of the two apostles in "Clement of Rome" (p. 357). Döllinger adds: "That S. Peter worked in Rome is a fact so abundantly proved and so deeply imbedded in the earliest Christian history, that whoever treats it as a legend ought in consistency to treat the whole of the earliest church history as legendary, or at least, quite uncertain. His presence in Corinth is obviously connected with his journey to Rome, and no one will accept the one and deny the other (see Cor. i. 12; iii. 22; xi. 22, 23; Clement's Ep. 47, etc.) Clement again reminds the Corinthians of the 'martyrdom of Peter and Paul ... among us,' meaning Rome. The very mention implies that S. Peter's martyrdom was a well-known fact, and it is inconceivable that his execution should have been known and not the place where it occurred, or that the place could have been forgotten, and a wrong one substituted some years later. And when Ignatius writes to the Romans—'I do not command you like Peter and Paul; they were apostles'—it is clear, without any explanation, that he desires to remind them of the two men who, as founders and teachers, had been the glory of the Church."
The Ebionite document, called "The Preaching of Peter," produced about the time of Ignatius, or very soon after, and used by Heracleon in Hadrian's time, is manifestly founded on the undisputed fact of S. Peter having labored at Rome. It is inconceivable that the author of the Ebionite document should have put forward a groundless fable, about the theatre of S. Peter's operations, at a time when many who had seen him must have been still alive. Eusebius, who had the writings of Papias (and Hegesippos) before him, maintains with Clement, that S. Peter wrote his Epistle at Rome (Euseb. ii. 15). Papias, a disciple of S. John, speaking of this epistle declares that "Babylon" means expressly the capital of the empire. Hegesippos, a Christian Jew of Palestine, who came to Rome in the first half of the second century, makes Linus the first bishop after the apostles, in accordance with Irenæus, who says: "After Peter and Paul had founded the Roman church and set it in order, they gave over the episcopate to Linus." If we consider that Hegesippos came to Rome to investigate, among other things, the succession of local bishops for the short period of eighty-three years, that he certainly spoke with persons whose fathers could remember the presence of the apostles, we cannot help accepting his evidence as conclusive.