This branch of the road courses through a gently rolling upland plain at the foot of the Martani mountain range, an area that had been heavily populated since the middle of the Bronze Age.

During his reign a number of major works were initiated, eventually including the amphitheater, most of the forum, and the marble-clad Arch of Trajan (now called the Arco di San Damiano).

Its bucolic setting, its large complex of mineralized thermal baths, theaters, temples and other public amenities, attracted wealthy and even middle class "tourists" from Rome.While many of the other mentioned towns and cities on the two branches of the old Roman road continue to exist, nothing but ruins remains of Carsulae, which was abandoned and never resettled.

For centuries Carsulae was mostly used as a quarry for building materials by nearby towns like San Gemini, Acquasparta, Massa Martana, Terni, and Cesi, where Roman tombstones may be seen built into the former church of S. Andrea.

No one knows the precise reasons why Carsulae was abandoned, but there are four reasons that seem plausible a) that it was destroyed and the site made inhospitable by an earthquake (however, most viable cities hit by earthquakes are rebuilt), b) that it lost its importance and becomes increasingly impoverished because most of the north–south traffic used East branch of the Via Flaminia (Terni, Spoleto, Foligno), c) Carsuale was built in a valley without defensive walls, in the early Middle Ages people tend to move to better defended settlements due to the political instability that sets in.

Gli scavi di Umberto Ciotti a cura di Paolo Bruschetti, Luca Donnini, Massimiliano Gasperini In 2004, after a thirty-year pause in excavation, under the supervision of inspector Paolo Bruschetti, a new excavation campaign was reopened at the Roman Baths directed by Prof. Jane Whitehead of Valdosta State University with the collaboration of the Associazione per la Valorizzazione del Patrimonio Storico San Gemini.