Along a very old road that connected the Stigliano thermal baths with the main route of Via Clodia lie the remains of an imposing structure. It is called the Ponte del Diavolo (the Devil’s Bridge) and was a viaduct of around 90 metres in length, 6 metres wide and 9 metres high, built to allow people to cross a ditch and the valley. 

It was constructed out of large blocks of peperino volcanic rock up to 2 metres long, fitted together in the “dry stone wall style”, without the use of any mortar. The precise date of the viaduct is not known but an initial examination of the building techniques used, which reveal clear signs of Etruscan influences, make it seem highly likely that the bridge dates from the end of the Republican period in the 1st century BC.