But more especially was it built to be the lower support for a gigantic water reservoir which extends under nearly the whole width of this terrace from about Corso Pierluigi No. 88 almost to the Cathedral.^[43] The four sides of this great reservoir are also of opus quadratum laid header and stretcher.

The lower wall, the real town wall, is a wall only in appearance, for it has but one thickness of blocks, set header and stretcher in a mass of solid concrete.^[44] This wall makes very clear the impregnability of even the lower part of Præneste, for the wall not only occupies a good position, but is really a double line of defense. There are here two walls, one above the other, the upper one nineteen feet back of the lower, thus leaving a terrace of that width.^[45] At the east, instead of the lower solid wall of opus quadratum, there is a series of fine tufa arches built to serve as a substructure for something. It is to be remembered again that between the arches on the east and the solid wall on the west is a stretch of 200 feet of opus incertum, and a space where there is no wall at all. This lower wall of Præneste occupies the same line as the ancient wall and escarpment, but the most of what survives was restored in Sulla's time. The opus quadratum is exactly the same style as that in the Tabularium in Rome.

Now, no one could see the width of the terrace above the lower wall, without thinking that so great a width was unnecessary unless it was to give room for a road.^[46] The difficulty has been, however, that the line of arches at the east, not being in alignment with the lower wall on the west, has not been connected with it hitherto, and so a correct understanding of their relation has been impossible.

Before adducing evidence to show the location of the main and triumphal entrance to Præneste, we shall turn to the town above for a moment to see whether it is, a priori, reasonable to suppose that there was an entrance to the city here in the center of its front wall. If roads came up a grade from the east and west, they would join at a point where now there is no wall at all. This break is in the center of the south wall, just above the forum which was laid out in Sulla's time on the level spot immediately below the town. Most worthy of note, however, is that this opening is straight below the main buildings of the ancient town, the basilica, which is now the cathedral, and the temple of Fortuna. But further, a fact which has never been noticed nor accounted for, this opening is also in front of the modern square, the piazza Garibaldi, which is in front of the buildings just mentioned but below them on the next terrace, yet there is no entrance to this terrace shown.^[47] It is well known that the open space south of the temple, beside the basilica, has an ancient pavement some ten feet below the present level of the modern piazza Savoia.^[48] Proof given below in connection with the large tufa base which is on the level of the lower terrace will show that the piazza Garibaldi was an open space in ancient times and a part of the ancient forum. Again, the solarium, which is on the south face of the basilica,^[49] was put up there that it might be seen, and as it faces the south, the piazza Garibaldi, and this open space in the wall under discussion, what is more likely than that there was not only an open square below the basilica, but also the main approach to the city?

But now for the proof. In 1756 ancient paving stones were still in situ^[50] above the row of arches on the Via degli Arconi, and even yet the ascent is plain enough to the eye. The ground slopes up rather moderately along the Via degli Arconi toward the east, and nearly below the southeast corner of the ancient wall turned up to the west on these arches, approaching the entrance in the middle of the south wall of the city.^[51] But these arches and the road on them do not align exactly with the terrace on the west. Nor should they do so. The arches are older than the present opus quadratum wall, and the road swung round and up to align with the road below and the old wall or escarpment of the city above. Then when the whole town, its gates, its walls, and its temple, were enlarged and repaired by Sulla, the upper wall was perfectly aligned, a lower wall built on the west leaving a terrace for a road, and the arches were left to uphold the road on the east. Although the arches were not exactly in line, the road could well have been so, for the terrace here was wider and ran back to the upper wall.^[52] The evidence is also positive enough that there was an ascent to the terrace on the west, the one below the Barberini gardens, which corresponds to the ascent on the arches. This terrace now is level, and at its west end is some twenty feet above the garden below. But the wall shows very plainly that it had sloped off toward the west, and the slope is most clearly to be seen, where a very obtuse angle of newer and different tufa has been laid to build up the wall to a level.^[53] It is to be noticed too that this terrace is the same height as the top of the ascent above the arches. We have then actual proofs for roads leading up from east and west toward the center of the wall on the south side of the city, and every reason that an entrance here was practicable, credible, and necessary.

But there is one thing more necessary to make probabilities tally wholly with the facts. If there was a grand entrance to the city, below the basilica, the temple, and the main open square, which faced out over the great forum below, there must have been a monumental gate in the wall. As a matter of fact there was such a gate, and I believe it was called the PORTA TRIUMPHALIS. An inscription of the age of the Antonines mentions "seminaria a Porta Triumphale," and this passing reference to a gate with a name which in itself implies a gate of consequence, so well known that a building placed near it at once had its location fixed, gives the rest of the proof necessary to establish a central entrance to the city in