From the summit of the mountain, where the arx or citadel was, it becomes clear at once why Praeneste occupied a proud and commanding position among the towns of Latium. The city, clambering up the slope on its terraces, occupied a notably strong position[1], and the citadel was wholly impregnable to assault. Below and south of the city stretched fertile land easy of access to the Praenestines, and sufficiently distant from other strong Latin towns to be safe for regular cultivation. Further, there is to be added to the fortunate situation of Praeneste with regard to her own territory and that of her contiguous dependencies, her position at a spot which almost forced upon her a wide territorial influence, for Monte Glicestro faces exactly the wide and deep depression between the Volscian mountains and the Alban Hills, and is at the same time at the head of the Trerus-Liris valley. Thus Praeneste at once commanded not only one of the passes back into the highland country of the Aequians, but also the inland routes between Upper and Lower Italy, the roads which made relations possible between the Hernicans, Volscians, Samnites, and Latins. From Praeneste the movements of Volscians and Latins, even beyond the Alban Hills and on down in the Pontine district, could be seen, and any hostile demonstrations could be prepared against or forestalled. In short, Praeneste held the key to Rome from the south.
Monte Glicestro is of limestone pushed up through the tertiary crust by volcanic forces, but the long ridges which run off to the northwest are of lava, while the shorter and wider ones extending toward the southwest are of tufa. These ridges are from three to seven miles in length. It is shown either by remains of roads and foundations or (in three cases) by the actual presence of modern towns that in antiquity the tip of almost every one of these ridges was occupied by a city. The whole of the tufa and lava plain that stretches out from Praeneste toward the Roman Campagna is flat to the eye, and the towns on the tips of the ridges seem so low that their strong military position is overlooked. The tops of these ridges, however, are everywhere more than an hundred feet above the valley and, in addition, their sides are very steep. Thus the towns were practically impregnable except by an attack along the top of the ridge, and as all these ridges run back to the base of the mountain on which Praeneste was situated, both these ridges and their towns necessarily were always closely connected with Praeneste and dependent upon her.