The original Umbrian civilization was succeeded by Roman dominion. In 220 B.C., during the first wave of Roman expansion, the censor Gaius Flaminius undertook the construction of a major route (the Via Flaminia) to connect Rome to the northern Adriatic coast. The federate centre of Helvillum Vicus (Fossato di Vico); the municipium of Suillum (Sigillo) and the statius of Ad Ensem (Scheggia) remained within the political and cultural orbit of Rome, although later coming under Byzantine control. These towns and their surrounding territory formed part of a corridor which permanently united Rome and Ravenna, resisting under pressure from the Lombardy dukedoms.

The fortification of Castrum Costacciari (Costacciaro) was constructed by the Commune of Gubbio in about 1250 to defend its eastern boundary, together with Scheggia. Sigillo and Fossato, on the other hand, formed part of the territory of the Commune of Perugia, guaranteeing, by means of the road through the pass, access to the salt markets of the Adriatic. The archeological finds linked to the Via Flaminia are of great importance. They are conserved in the antiquarium and some monuments can still be seen in their original setting, like the Pontespiano Roman bridge.

The historical centres of the four towns are attractive and culturally important. They contain many defensive towers and walls, churches, paintings, collections of fossils and rare historical documents. In the northern part of the territory there are many Benedictine and Camaldolite abbeys, the most important of which are those of Saint Emiliano at Isola Fossara and the monastery of Saint Girolamo at Pascelupo.