In the earliest city of Rome, to which we are carried back by tradition or archaeological research, this development has already been attained. The square city (_Roma quadrata_) was the enclosure of the Palatine, the “grazing-land” of the early Roman shepherd;[5] the bounds of the oldest _pomerium_ were known in later times to have been the limits of this site,[6] and traces of the tufa ring-wall may yet be seen. From this centre the city spread in irregular concentric circles.[7] Traces of ritual have preserved a memory of a city of the seven hills (_Septimontium_)—not those of the Servian Rome, but five smaller elevations, three (Palatium, Cermalus, Velia) on the older city of the Palatine, and two (Oppius, Cispius) on the newly-included Esquiline; while two valleys on the latter (Fagutal and Subura) also bear the name _montes_,[8] and are, with the sites that really deserve the name, inhabited by the _montani_, who are distinguished from the _pagani_, the inhabitants of the lower-lying land beneath. It is not impossible that these seven “hills” were once the sites of independent or loosely connected villages (_vici_, or perhaps even _pagi_) which were gradually amalgamated under a central power, and, as the walls of the state could never have been coterminous with its territory, each successive enclosure must show the incorporation, voluntary or enforced, of a far greater number of smaller political units than those which the fortifications directly absorbed. Modern inquirers, following up a further hint supplied by the survival of a ritual, have held that there was another advance before the epoch of the Servian Rome was reached, and that what is known as “the Rome of the four regions” survives in the sites associated with the chapels of the Argei,[9] and is preserved in the administrative subdivisions of the city to the close of the Republic.[10] To form these regions the Caelian, the Quirinal, and the Viminal hills were added, while the Capitol with its two peaks now became, not indeed a part of the town, but, as the “head” of the state, its chief stronghold and the site of its greatest temples. The final step in the city’s growth was the enclosure associated with the name of Servius Tullius, a fortification extending beyond the limits of the true _pomerium_, which added to the city the whole of the Esquiline to the north-east, the Aventine to the south-west, stretched to the west to the bank of the Tiber where the Pons Sublicius crosses the river, and formed the enceinte of Republican Rome.