"Les enfants qui foulent le raisin, tels qu'on les voit dans les mosaïques de l'église de Sainte Constance, les bas-reliefs de son tombeau et ceux de beaucoup d'autres tombeaux chrétiens sont bien d'origine païenne, car on les voit aussi figurer dans les bas-reliefs où paraît Priape."—Ampère, Hist. Rom. iii. 257.
Behind the two churches is an oblong space, ending in a fine mass of ruin, which is best seen from the valley below. This was long supposed to be the Hippodrome of Constantine, but is now discovered to have belonged to an early Christian cemetery.
The Catacomb of St Agnese is entered from a vineyard about a quarter of a mile beyond the church. It is lighted and opened to the public on St. Agnes' Day. After those of St. Calixtus, this, perhaps, is the catacomb which is most worthy of a visit.
We enter by a staircase attributed to the time of Constantine. The passages are lined with the usual loculi for the dead, sometimes adapted for a single body, sometimes for two laid together. Beside many of the graves the palm of victory may be seen scratched on the mortar, and remains of the glass bottles or ampullæ, which are supposed to indicate the graves of martyrs, and to have contained a portion of their blood, of which they are often said to retain the trace. One of the graves in the first gallery bears the names of consuls of A.D. 336, which fixes the date of this part of the cemetery.
The most interesting features here are a square chamber hewn in the rock, with an arm-chair (sedia) cut out of the rock on either side of the entrance, supposed to have been a school for catechists,—and near this is a second chamber for female catechists, with plain seats in the same position. Opening out of the gallery close by is a chamber which was apparently used as a chapel; its arcosolium has marks of an altar remaining at the top of the grave, and near it is a credence-table; the roof is richly painted,—in the central compartment is our Lord seated between the rolls of the Old and New Testament. Above the arcosolium, in the place of honour, is our Saviour as the Good Shepherd, bearing a sheep upon his shoulders, and standing between other sheep and trees;—in the other compartments are Daniel in the lions' den, the Three Children in the furnace, Moses taking off his shoes, Moses striking the rock, and—nearest the entrance—the Paralytic carrying his bed. A neighbouring chapel has also remains of an altar and credence-table, and well-preserved paintings,—the Good Shepherd, Adam and Eve, with the tree between them, Jonah under the gourd, and in the fourth compartment a figure described by Protestants merely as an Orante, and by Roman Catholics as the Blessed Virgin.[244] Near this chapel we can look down through an opening into the second floor of the catacomb, which is lined with graves like the first.
In the further part of the catacomb is a long narrow chapel which has received the name of the cathedral or basilica. It is divided into three parts, of which the furthest, or presbytery, contains an ancient episcopal chair with lower seats on either side for priests—probably the throne where Pope St. Liberius (A.D. 359) officiated, with his face to the people, when he lived for more than a year hidden here from persecution. Hence a flight of steps leads down to what Northcote calls "the Lady Chapel," where, over the altar, is a fresco of an orante, without a nimbus, with outstretched arms,—with a child in front of her. On either side of this picture, a very interesting one, is the monogram of Constantine, and the painting is referred to his time. Near this chapel is a chamber with a spring running through it, evidently used as a baptistery.
At the extremity of the catacomb, under the basilica of St. Agnes, is one of its most interesting features. Here the passages become wider and more irregular, the walls sloping and unformed, and graves cease to appear, indicating one of the ancient arenaria, which here formed the approach to the catacomb, and beyond which the Christians excavated their cemetery.
The graves throughout almost all the catacombs have been rifled, the bones which they contained being distributed as relics throughout Roman Catholic Christendom, and most of the sarcophagi and inscriptions removed to the Lateran and other museums.
"Vous pourriez voir ici la capitale des catacombes de toute la chrétienté. Les martyrs, les confesseurs, et les vierges, y fourmillent de tous côtés. Quand on se fait besoin de quelques reliques en pays étrangers, le Pape n'a qu'à descendre ici et crier, Qui de vous autres veut aller être saint en Pologne? Alors, s'il se trouve quelque mort de bonne volonté, il se lève et s'en va."—De Brosses, 1739.
Half a mile beyond St' Agnese, the road reaches the willow-fringed river Anio, in which "Silvia changed her earthly life for that of a goddess," and which carried the cradle containing her two babes Romulus and Remus into the Tiber, to be brought to land at the foot of the Palatine fig-tree. Into this river we may also recollect that Sylla caused the ashes of his ancient rival Marius to be thrown. The river is crossed by the Ponte Nomentana, a mediæval bridge, partially covered, with forked battlements.