The route runs through a quite populated area, so much that even a thirty-metre-high cascade flows just in the centre of Isola del Liri. Let us have a coffee or an ice cream in this pretty village, while admiring the impressive waterfall. From Isola di Liri, we proceed towards Arpino, following a stretch of the Liri River until the magnificent Cistercian Abbey of San Domenico in Sora, founded in 1011 by San Domenico di Sora on the ruins of Cicero’s Villa. Worth visiting is the crypt, where the Saint is buried. As an alternative, those who want to directly reach Arpino from Isola di Liri can choose a six kilometre shorter variant. The itinerary continues along the Fibreno watercourse, a tributary of the Liri River, then climbs up to Arpino, where we will pay a visit to the ancient Acropolis of Civitavecchia, with its megalithic walls and a unique example of pointed arch in Italy.