Between the Tiber and Garigliano, as well as between the Arno and Tiber, there exist extensive remains of Cyclopean masonry, as well as walls of hewn and squared stones. The former were predominant in the mountainous interior, as at Alatrium, Arpinum, Aurunca, Cora, Cures, Ecetræ, Ferentinum, Medullia, Norba, Præneste, Signia, Sora, Tibur, Verulæ, etc.; the latter in the low rolling land between the Apennines and the Tyrrhenian Sea, as at Æsernia, Antium, Ardea, Aricia, Aufidena, Lavinium, Politorium or Apiolæ, Satricum, Scaptia, Tellenæ, Tusculum, and Rome. They frequently occur in contemporary works, as, for example, in the well-preserved polygonal ruins of Norba and Signia (the present Norma and Segni) and the horizontal courses of the Servian fortification, both of which constructions date from the period of the later kings. The age of these works can usually be roughly estimated: the Cyclopean walls of Olevano, of enormous unhewn boulders, like the fortifications of Tiryns, are evidently of greater antiquity than the carefully fitted polygonal masonry of Norba and Signia (Fig. 264), where the separate stones are tooled to plane faces and sides; while the irregular horizontal courses of unequal thickness, which form the older Latin ramparts, precede, in point of time, the exactly jointed blocks of the Servian walls of Rome. A more exact classification or chronological determination is not possible.
Among all the remains of primitive walls in Italy, those of Rome are naturally the most interesting. It unfortunately cannot be definitely proved that a part of a rampart upon the western corner of the Palatine, excavated thirty years ago from the rubbish and brick revetment of the imperial period, appertained to the fortifications which surrounded the city of Romulus. But this masonry, though not perhaps attributable to the eighth century, is certainly of an early age of Roman history. It is formed of oblong stones, exactly hewn, and laid in courses of stretchers and headers, without the use of mortar, the careful jointing showing a high degree of technical perfection. The better-authenticated remains of the circuit wall of Servius Tullius are similar in character. They have been best preserved upon the southern slope of the Aventine, east of the Via di S. Prisca, where they attain a height of 10 m., with a length of 30 m. (Fig. 265.) The arrangement of the jointing, however, is not so well considered as that in the former example, the vertical interstices of adjoining courses being frequently continuous.
The passage formed a small vestibule or chamber in the thickness of the wall, which required inner and outer portals, like those of the Temple of Janus upon the Velabrum, which, long after the ruin of the Servian fortifications, and even down to the time of the empire, were sacredly preserved as relics. A similar arrangement existed in Etruria even more frequently than in the Latin cities.
The Roman gates were so doubled as to form two passages side by side—one for entrance, the other for exit; a comparatively narrow opening could thus provide ample space for those moving only in the same direction. It is not certainly known how these Roman gates were covered. The oldest vestiges of masonry in Latium show no traces of vaulting, while other means of accomplishing the connection have been preserved almost intact, such as the heavy lintels upon vertical or inclined jambs, as at Segni, Circello, Alatri, and Olevano; or the gradual projection of the horizontal courses beyond those beneath them, as at Arpino. The primitive houses for springs, and the so-called Mamertine Prison, show that vaulting was not practised in Rome or the neighboring Latin cities during the early ages; the Prison, probably built in the time of Servius Tullius, appears to have been somewhat similar in construction to the Greek tholos. A further example of this kind is the chamber for a fountain in Tusculum, where the stone slabs of the ceiling lean so as to form a sort of continuous gable.
Rome owed more to the last fifty years of its hated kings than to the two following centuries. From the royal period dates one of the most important monuments of vaulted construction, the Cloaca Maxima of Rome, built in the reign of Tarquinius Superbus, and probably under the direction of engineers from his native Etruria. To this gigantic work, admired even in the time of the magnificent Roman empire, is undoubtedly owing the preservation of the Eternal City, which it has secured from the swamping that has befallen its neighboring plains. Its quarried stones are still visible beneath the later brick arches in the vicinity of S. Giorgio in Velabro. (Fig. 266.) The building of drains naturally led to extensive works upon the banks of the river, which protected the thickly populated city; it was forgotten that, in earlier ages, it had often been necessary to traverse the Velabrum in boats, and that the spring freshets had extended a sheet of water between the Palatine and Capitoline hills.
