In Roman times, Pliny the Elder said Trevi was a city of the old Umbrians, and an old stone with Umbrian writing was found in the comune, at Bovara, in the 1950s. ""Treviae"" is also listed in the 5th‑century Bordeaux Itinerary. We do not know the history of Trevi in very old times, although some walls in the center part of the town on the hill are as old as the 1st century BC. Trevi started to spread out away from the hill during the time of the Empire, when Hadrian fixed the main road in the area, the Via Flaminia; this made a small town in the plain grow, at a place now called Pietrarossa. For hundreds of years people have been finding old things there: there were Roman baths that people were probably using in the time of St. Francis, who came here and told people to bathe in them.