If we depart from Narni, the quickest and most modern road, desired by Emperor Augustus to facilitate the movement of his troops, deserves a minor deviation for the moment. At the gates of Terni, we stop to admire another feat of Roman engineering: the Cascata delle Marmore (the Marble Waterfall), which was built in 290 BC by the Consul Curio Dentato. The waterfall was constructed to transport the waters from the Velino River and the Reatina Plains, where they stagnated into a swamp, to the Nera River, after a drop of 165 meters. (almost 400 ft)