All these Hernican cities were on the north side of the valley, but one naturally groups with them Signia, on the south side, not only because, though it is a Latin and not a Hernican city, it is built in a similar style to Alatri and Ferentino, but because it joined hands with the Hernican cities in the early wars.
A sunrise from the top of Mount Soracte and from the acropolis at Segni are among the delights one remembers for many years. Signia is higher than any of the cyclopean cities we are studying,higher even than Praeneste,standing over two thousand feet (six hundred sixty-eight meters) on the highest northern spur of the Volscian mountains, separated from the range by a narrow valley. A colony was sent here, according to Livy and Dionysius, by Tarquinius Superbus in 510 B.C., and it was rein-forced or restored in 495. It stands on a spur which projects from the mountain at a height of five hundred sixty-seven meters, and then rises to six hundred sixty-eight meters at the extreme end where the city was built somewhat in the same way as Praeneste. The Aequians had passed in beyond it toward the Alban hills, reaching as far as Velitrae; and Artena, which the Romans destroyed in 406 in the way I have quoted from Livy, was midway between them. Its natural strength was phenomenal and we have no record of its ever having been captured.
The modern town is ensconced in one corner of the ancient circuit of walls. These walls are among the most extraordinary and perfectly preserved in the whole cyclopean district. The ancient city was not as large as Anagnia, to which it corresponded as watch dog on the opposite side of the valley, or as Norba, which was its twin guardian on the other side of the mountain. The reason is evident. The site was not selected because it commanded a fertile plain. On the contrary, it was too far in the hills. It was mainly a military station. The modern schools attribute its foundation and the building of its walls to about the year 495, when the Roman military camp was said to have been converted into a permanent military colony. In my opinion, however, the city pre-existed and simply received a Roman garrison at that time. How many centuries before this I would not venture to suggest ; probably two or three. Aside from the general proposition that I believe most walls of polygonal or cyclopean masonry to antedate this period of 495 B.C., two facts seem to me to point in this direction. These are : the city gates and the temple on the acropolis. Three main gates have been identified. The most conspicuous one, popularly called Porta Saracinesca, on the north side, is typical of them all. It is built of enormous blocks, carefully bedded, and the upper stone on each side cut diagonally so as to shorten the space necessary to be covered by the architrave block. When we remember that the gates of Cosa and Norba were built apparently for wooden architraves, which was certainly a disadvantage and a defect in construction, it is a temptation to see in this scheme at Segni a later device to secure an all-stone gateway. But when we remember also the great age of the gallery at Tiryns with its similar arrangement, and the primitive gate at Arpinum, it seems more likely that the two schemes belonged rather to different schools than to different ages.
This Porta Saracinesca is interesting for its peculiar relationship to the city wall. It is not an opening in the walls, but built on at right angles to them, with the object of forcing the enemy to expose their unprotected right side in an attack, according to the scheme already noticed in the round-arched gate at Ferentino. It produces a short angle, breaking the circuit-curve of the walls, and marks an advance in method : the other gates, such as those of S. Pietro and in Lucino, are built on the same scheme. A sally port with flat architrave opens in the walls not far from the Porta Saracinesca to the east, and a second one farther on in the wall. The wall circuit has the primitive characteristic of not being built in the least on a level but of following the undulations of the hill. The arrangement at Norba with its artificial terraces and levels is far less archaic. This is another argument for the antiquity of the wall of Segni, as the terraces at Norba seem to date from about 490 B.C. Signia, therefore, antedates the arrival of the Romans.
The acropolis is comparatively insignificant, and the main defense must have been the city walls. Here, however, are two notable buildings, the cistern and the temple, which stand close together. The cistern is an enormous circular well, with a diameter of about sixty-five feet (21.50 meters), built not of polygonal masonry like those in other cyclopean cities, but of quadrangular blocks of peperino on a foundation of opus signinum. As to the temple there is a heated controversy which makes of it one of the crucial monuments of the early Roman age. It rises on a three-stepped basement such as has been claimed to form the base for the open-air hieron or shrine of the primitive Latins, Sabines and other Italian races before the introduction of temples. These triple, pyramidal bases for worship can be traced in a number of early sites in Samnium, Sabina and elsewhere, but this one at Signia is not only well preserved but supports an antique temple cella which has been converted into a church still in use. The basement, about ten feet high, is of the same polygonal blocks of white limestone as the walls, with the greater approach to horizontality required to pass to the flat top line and the square corners. But the temple cella resting on it is built of squared peperino blocks in regular courses, such as we have already noted in the cistern. It has lost the columns which probably formed its portico, but the cella walls are still intact. It is by far the earliest known temple cella in Latium or Etruria, antedating any other by two or three centuries. It has a triple division to prove its dedication to the Roman Capitoline triad then introduced. I think all authorities agree in dating it from about the time of the establishment of the Roman colony in 510 or 495 B.C. The only difference of opinion is whether its triple foundation is contemporary or earlier, and whether the cella replaced a primitive open-air shrine. Probably the cella has lost its decorative features of stucco and terra-cotta, which we might supply from the finds at Satricum, Alatri and Civita Castellana or even Capua. It gives us, at all events, another solid fact upon which to base re-constructions of temples of the age of the Tar-Ruins. I believe that the triple base is earlier than the temple cella, and that the Romans, not using polygonal masonry, brought the volcanic peperino from a distance in order to use it for their course masonry in the new Capitolium cella, as well as in the cistern. The local limestone could not readily be used, as we know, for course masonry. Here, again, it was the style that determined the choice of material, not the reverse.
At the same time (c. 495?) the Romans added to the walls and built a double city gate with arched openings: all of peperino squared blocks. This gate formed the main approach of the new colony. It has been destroyed, but we may infer that it resembled the arched gate of Ferentino.