But in connection with this view of the position of Rome as the emporium of Latium another observation suggests itself. At the time when history begins to dawn on us, Rome appears, in contradistinction to the league of the Latin communities, as a compact urban unity. The Latin habit of dwelling in open villages, and of using the common stronghold only for festivals and assemblies or in case of special need, was subjected to restriction at a far earlier period, probably, in the canton of Rome than anywhere else in Latium. The Roman did not cease to manage his farm in person, or to regard it as his proper home; but the unwholesome atmosphere of the Campagna could not but induce him to take up his abode as much as possible on the more airy and salubrious city hills; and by the side of the cultivators of the soil there must have been a numerous non-agricultural population, partly foreigners, partly native, settled there from very early times. This to some extent accounts for the dense population of the old Roman territory, which may be estimated at the utmost at 115 square miles, partly of marshy or sandy soil, and which, even under the earliest constitution of the city, furnished a force of 3300 freemen; so that it must have numbered at least 10,000 free inhabitants. But further, every one acquainted with the Romans and their history is aware that it is their urban and mercantile character which forms the basis of whatever is peculiar in their public and private life, and that the distinction between them and the other Latins and Italians in general is pre-eminently the distinction between citizen and rustic. Rome, indeed, was not a mercantile city like Corinth or Carthage; for Latium was an essentially agricultural region, and Rome was in the first instance, and continued to be, pre-eminently a Latin city. But the distinction between Rome and the mass of the other Latin towns must certainly be traced back to its commercial position, and to the type of character produced by that position in its citizens. If Rome was the emporium of the Latin districts, we can readily understand how, along with and in addition to Latin husbandry, an urban life should have attained vigorous and rapid development there and thus have laid the foundation for its distinctive career.
It is far more important and more practicable to follow out the course of this mercantile and strategical growth of the city of Rome, than to attempt the useless task of chemically analysing the insignificant and but little diversified communities of primitive times. This urban development may still be so far recognized in the traditions regarding the successive circumvallations and fortifications of Rome, the formation of which necessarily kept pace with the growth of the Roman commonwealth in importance as a city.
The town, which in the course of centuries grew up as Rome, in its original form embraced according to trustworthy testimony only the Palatine, or "square Rome" (Roma quadrata), as it was called in later times from the irregularly quadrangular form of the Palatine hill. The gates and walls that enclosed this original city remained visible down to the period of the empire: the sites of two of the former, the Porta Romana near S. Giorgio in Velabro, and the Porta Mugionis at the Arch of Titus, are still known to us, and the Palatine ring-wall is described by Tacitus from his own observation at least on the sides looking towards the Aventine and Caelian. Many traces indicate that this was the centre and original seat of the urban settlement. On the Palatine was to be found the sacred symbol of that settlement, the "outfit-vault" (mundus) as it was called, in which the first settlers deposited a sufficiency of everything necessary for a household and added a clod of their dear native earth. There, too, was situated the building in which all the curies assembled for religious and other purposes, each at its own hearth (curiae veteres). There stood the meetinghouse of the "Leapers" (curia Saliorum) in which also the sacred shields of Mars were preserved, the sanctuary of the "Wolves" (Lupercal), and the dwelling of the priest of Jupiter. On and near this hill the legend of the founding of the city placed the scenes of its leading incidents, and the straw-covered house of Romulus, the shepherd's hut of his foster-father Faustulus, the sacred fig-tree towards which the cradle with the twins had floated, the cornelian cherry-tree that sprang from the shaft of the spear which the founder of the city had hurled from the Aventine over the valley of the Circus into this enclosure, and other such sacred relics were pointed out to the believer. Temples in the proper sense of the term were still at this time unknown, and accordingly the Palatine has nothing of that sort to show belonging to the primitive age. The public assemblies of the community were early transferred to another locality, so that their original site is unknown; only it may be conjectured that the free space round the mundus, afterwards called the area Apolliniswas the primitive place of assembly for the burgesses and the senate, and the stage erected over the -mundus- itself the primitive seat of justice of the Roman community.
The "festival of the Seven Mounts" (septimontium), again, has preserved the memory of the more extended settlement which gradually formed round the Palatine. Suburbs grew up one after another, each protected by its own separate though weaker circumvallation and joined to the original ring-wall of the Palatine, as in fen districts the outer dikes are joined on to the main dike. The "Seven Rings" were, the Palatine itself; the Cermalus, the slope of the Palatine in the direction of the morass that extended between it and the Capitol towards the river (velabrum); the Velia, the ridge which connected the Palatine with the Esquiline, but in subsequent times was almost wholly obliterated by the buildings of the empire; the Fagutal, the Oppius, and the Cispius, the three summits of the Esquiline; lastly, the Sucusa, or Subura, a fortress constructed outside of the earthen rampart which protected the new town on the Carinae, in the depression between the Esquiline and the Quirinal beneath S. Pietro in Vincoli. These additions, manifestly the results of a gradual growth, clearly reveal to a certain extent the earliest history of the Palatine Rome, especially when we compare with them the Servian arrangement of districts which was afterwards formed on the basis of this earliest division.