One entered the chamber in antiquity--it was always underground--down a long vaulted ramp which made a right-angle turn and emerged in a little square vestibule, whose skylight provided the basilica’s only natural light. Beyond the vestibule was a vaulted nave (Fig. 7.8) ending in an apse, and two side aisles. The profiles of the piers upholding the vaults, and of the arches connecting the nave with the side aisles, are irregular; and the piers are set at eccentric angles (Fig. 7.9): this suggests a curious method of construction. A trench must have been dug through the surface tufa corresponding to the desired perimeter of the building. Then six square pits were dug, one for each pier, and the outline of the arches and doorways formed in the virgin soil. Then mortar was poured in. When it had set, the entrance corridor was dug and the interior of the basilica emptied of earth through the skylight in the vestibule. Then vault, piers, and walls were stuccoed. In the late Republic and after, Roman artisans showed great skill in ornamental stucco-work, a far cry from the wattle-and-daub, in the primitive huts, which is the remote ancestor of the refined work in the basilica, and a symbol of how far on the road to sophistication Rome had traveled from her humble beginnings. [Illustration: FIG. 7.9 Rome, subterranean basilica at Porta Maggiore. (_Legacy of Rome_, p. 407)] In the basilica the stucco-work is divided by moldings into squares, rectangles, and lozenges, filled with figures in low relief of great delicacy and elegance. Some are simple scenes of daily life, and many others are part of the standard repertory of Roman art, but the key motifs will bear, as we shall see, a single, serious interpretation. The apse, the focal point of the whole structure, was reserved for a special scene of central importance. The central panel of the central vault shows a naked human figure, a pitcher in his hand, carried off by a winged creature. (The interior of the figure is eaten out; this is due not to vandalism but to the depredations of a parasitic insect related to the termite.) In the four surrounding panels are four other motifs. A hero wearing a lion’s skin shoots with a bow a monster guarding a maiden chained to a rock. A beautiful, seated, half-naked woman cradles a statuette in her left arm; a bearded middle-aged man stands before her. A young man in a short tunic, carrying a leafy branch or a shepherd’s crook, leads off a woman by the hand. A veiled female figure takes from a tree guarded by a serpent a fleecy object to give to a man kneeling on a table nearby. How are these scenes to be interpreted? Do they share a common motif? According to the French Professor Jérome Carcopino, they do.