used as altars for the celebration of the eucharist, and eventually grave abuses arose from the superstitious veneration paid to the relics of the martyr or confessor interred therein. Frequently, also, the back of this arched recess was pierced with graves of a later date, often directly through a painting,[18] in order to obtain a resting place near the bodies of the saints.
Fig. 14.—Section of the Catacomb of Callixtus.
Hitherto only one level of the Catacombs has been described, but frequently “beneath this depth there is a lower deep,” or even three or four tiers of galleries, excavated as the upper ones became filled with graves. Thus there are sometimes as many as five stories, or piani, as they are called, one beneath the other. These are carefully maintained horizontal, to avoid breaking through the floor of the one above or the roof of the one below, the danger of which would be very great if the strict level were departed from. For the same reason the different piani were generally separated by a thick stratum of solid tufa. The relative position of these levels is shown by the following engraving, reduced from De Rossi. It represents a section of the Crypt of St. Lucina, a part of the Cemetery of Callixtus. The dark colored stratum, marked I in the margin, is entirely made up of the débris of ancient monuments, buildings, and other materials accumulated in the course of ages in this place to the depth of eight feet. It has completely buried the ancient roads, except where excavated, as shown in the engraving. The next stratum, II, is of solid grayish tufa. In this the first level or piano, φ, is excavated. It is not more than twenty feet below the surface, and in many places only half that depth. Consequently its area is comparatively limited, because if extended it would have run out into the
open air, from the sloping of the ground in which it is dug. The next stratum, III, is softer and more easily worked, and therefore is that in which are found the most important and extensive piani of galleries. The cross sections P and X, and the longitudinal section υ, will show how the lower surface of the more solid stratum above was made the ceiling of these galleries, in order to lessen the danger of its falling. At B will be observed the employment of masonry to strengthen the
crumbling walls of the friable tufa. The descent of a few steps, some of which have been worn away, will also be noticed at U. At IV a more rocky stratum is found, called tufa lithoide, below which the ancient fossors[19] had to go to find suitable material for the excavation of the third piano. This was found in stratum V, in which are two piani at different levels. The lower one is not vertically beneath that here represented above it, but at some little distance. It is here shown, to exhibit at one view a section of all the stories of this Catacomb. The upper piano, g, consists of low and narrow galleries, but the lower one, marked Γ Γ Γ, seventy-one feet beneath the surface of the ground, is of great extent. Several of the loculi, it will be perceived, are built of masonry, in consequence of the crumbling nature of the soil. The three large arcosolia will also be observed. The floor of this piano rests on a somewhat firmer stratum, in which is still another level of galleries, Ω Ω Ω, ten feet lower down. This lower level is generally subject to inundation by water, in consequence of the periodical rising of the adjacent Almone, the level of which is shown at a depth of one hundred and four feet, and that of the Tiber at one hundred and thirty-one feet, below the surface.
To secure immunity from dampness, which would accelerate decomposition and corrupt the atmosphere, the Catacombs were generally excavated in high ground in the undulating hills around the city, never crossing the intervening depressions or valleys. There is, therefore, no connection between the different cemeteries except where they happen to be contiguous, nor, as has been asserted, with the churches of Rome. Where a
Catacomb has been excavated in low ground, as in the exceptional case of that of Castulo on the Via Labicana, the water has rendered it completely inaccessible.
Access to these different piani is gained by stairways, which are sometimes covered with tile or marble, or built with masonry, or by shafts. The awful silence and almost palpable darkness of these deepest dungeons is absolutely appalling. They are fitly described by the epithet applied by Dante to the realms of eternal gloom: loco d’ogni luce muto—a spot mute of all light. Here death reigns supreme. Not even so much as a lizard or a bat has penetrated these obscure recesses. Nought but skulls and skeletons, dust and ashes, are on every side. The air is impure and deadly, and difficult to breathe. “The cursed dew of the dungeon’s damp” distills from the walls, and a sense of oppression, like the patriarch’s “horror of great darkness,” broods over the scene.