We start from Rontagnano (cemetery parking area) by walking toward trail 123 soon reaching a cut that possibly allows us to shorten the walk (trail 123d). The main trail 123 leads to Campaolo, a locality known for a farmer’s discovery of one of the largest ambers in Europe. This precious amber ovoid weighing 625 g. is preserved along with many other archaeological and mineralogical artifacts in the “Veggiani Collection.” The path curves to the southwest, still around the nature oasis; in particular, a detour leads to a place where specimens of Newts (Triturus carnifex) can be seen in a natural stone reservoir: these are salamander-like amphibians that live in still waters characterized by the absence of fish and pollution.
Following the last section of the trail, we arrive at the village of Rontagnano, located on the top of a hill between the Uso and Savio valleys. A Malatesta castle once stood there (12th century), some ruins of which still remain. The keep of the fortress was transformed into a bell tower in the 18th century. The nearby Church of St. Blaise preserves some interesting furnishings, including a 15th-century wooden kneeler and an 18th-century organ. The entire route is completed on foot in about 2h 30m.