The Vestals are, on the internal face of the north crowning slab, six in all; they are depicted veiled and arranged according to their age, as the difference in their stature clearly indicates. They are the virgines appointed by the Pontifex Maximus among the young aristocratic girls between six and ten years of age, who were to keep the sacred fire for three decades, according to the reform that Augustus himself had introduced. In the frieze they appear during the ceremony, headed by two apparitores and followed by the lictor Vestalium.