The next ridge must always have been one of the most important, for from above Cavamonte as far as Passerano, at the bottom of the ridge on the side toward Rome, connecting with the highway which was the later Via Latina, ran the main road through Zagarolo, Passerano, Corcolle, on to Tibur and the north.[14] As this was the other of the two great roads which ran to the north without getting out on the Roman Campagna, it is certain that Praeneste considered it in her territory, and probably kept the travel well in hand. With dependent towns at Zagarolo and Passerano, which are several miles distant from each other, there must have been at least one more town between them, to guard the road against attack from Tusculum or Gabii. The fact that the Via Praenestina later cut the Colle del Pero-Colle Seloa just below a point where an ancient road ascends the ridge to a place well adapted for a town, and where there are some remains,[15] seems to prove the supposition, and to locate another of the dependent cities of Praeneste. That the next ridge, the one on which Zagarolo is situated, was also part of Praeneste's territory, aside from the fact that it has always been part of the diocese of Praeneste, is clearly shown by the topography of the district. The only easy access to Zagarolo is from Palestrina, and although the town itself cannot be seen from the mountain of Praeneste, nevertheless the approach to it along the ridge is clearly visible. The country south and in front of Praeneste spreads out more like a solid plain for a mile or so before splitting off into the ridges which are so characteristic of the neighborhood. East of the ridge on which Zagarolo stands, and running nearly at right angles to it, is a piece of territory along which runs the present road (the Omata di Palestrina) to the Palestrina railroad station, and which as far as the cross valley at Colle dell'Aquila, is incontestably Praenestine domain. But the territory which most certainly belonged to Praeneste, and which was at once the most valuable and the oldest of her possessions is the wide ridge now known as the Vigne di Loreto, along which runs the road to Marcigliano.[16] Not only does this ridge lie most closely bound to Praeneste by nature, but it leads directly toward Velitrae, her most advantageous ally. Tibur was perhaps always Praeneste's closest and most loyal ally, but the alliance with her had not the same opportunity for mutual advantage as one with Velitrae, because each of these towns commanded the territory the other wished to know most about, and both together could draw across the upper Trerus valley a tight line which was of the utmost importance from a strategic point of view. These two facts would in themselves be a satisfactory proof that this ridge was Praeneste's first expansion and most important acquisition, but there is proof other than topographical and argumentative.