Note 56 — Chapter IV · PART I. THE AQUEDUCTS.

The name of Porta Esquilina is here given to the Porta Maggiore, the outer gate on the road to the Esquiline. The same name was also given to the inner gate in the agger of Servius Tullius; but there must always have been an outer gate also in the outer mœnia, or bank and wall for enclosure, which was a necessary part of every fortified city. (The same name, Porta Angelica, is still given to both the inner and the outer gate of the Leonine City, near the Vatican.) The high streams were carried on this bank to the Porta Viminalis of Frontinus, now called the Porta di S. Lorenzo. The remains of these three aqueducts can be plainly seen on entering through the city wall close to the Porta Maggiore, on the north side, and going along on this bank to the Porta di S. Lorenzo. The specus is visible at both ends, carried on arches. In the middle the ground is higher, and the specus pass through it underground, and then emerge and are carried again upon arches, exactly as described by Frontinus. The Aqua Felice is carried over the three aqueducts of the Marcian arcade; it is on arches twenty feet from the ground at each end, and in the middle, where these three are underground. The lower part of the specus of the Aqua Felice almost touches the ground, while the other three are underground.