The ruins of the Roman city of Carsulae are located a short distance from Terni and the town of Sangemini, known for the presence of mineral springs. The city was born along the Via Flaminia and in function of it, as a center of aggregation of the pre-Roman populations residing on the hills and in the nearby countryside: in fact the territory was very heavily frequented since the Middle Bronze Age, with settlements on strong positions, at the peak of reliefs that dominated the underlying plains and the natural communication routes. The opening of the Via Flaminia, traced between 220 and 219 BC, represented a moment of great development for the neighboring populations, who took it as a reference point for the transformation and evolution of their way of life. The traffic that took place along the artery stimulated the transfer of populations to the areas it crossed; and it is probably in this phase that the center of Carsulae was built.
The excavations, which followed in a disorderly manner starting from the 16th century, and culminated in intensive campaigns between 1951 and 1972, brought to light a large number of monuments and building structures, as well as a series of inscriptions, from which it derives the image of a rich and politically active municipality, whose inhabitants were governed by important magistrates and gathered in trade associations.
The choice of the site was dictated, as mentioned, by mainly economic reasons, linked to the presence of a large communication route along which traffic took place between Rome and the Adriatic and more generally towards northern Italy; being then on the edge of a fertile plain allowed a profitable agriculture; the decline of Carsulae and its abandonment were on the other hand in direct relationship with the loss of importance of the western branch of the Flaminia, to the benefit of that for Interamna and Spoletium. Of the republican urban phase, in the period coinciding with the opening of the road, there are limited traces recovered in the excavation of the substructures of the temples of the forum. However, the definitive urban layout dates back to the Augustan age, when the city obtained the municipal constitution and was assigned to the Clustumina tribe. The definitive decline of the place was determined - as well as by the displacement of the main route of the Flaminia towards the Spoleto plain, and consequently by the abandonment of the "Carsulano" branch - also by serious natural events, including a strong earthquake that caused among other things, the collapse of some sinkholes on which many public and private buildings were set up and which made an already heavily impoverished site inhospitable. Carsulae is not mentioned as an episcopal see; the only Christian presence consists in the transformation of a Roman building into the church of San Damiano, home to a small convent of nuns.