The Nera river, which starts in the heart of the Marche Apennines and flows down into the Tiber river some 116 km further downstream, is the seventh largest medium-range Italian river. Its power and its impetuosity have given rise over the millennia to one of the most fascinating and least ‘modernized’ landscapes that Umbria has to offer: Valnerina. A narrow and winding valley that crosses the whole of south-eastern Umbria and extends from the municipality of Preci, it include the territories of Terni to the south and Norcia and Cascia to the east. The Park develops from the middle-lower section of the river, from the village of Ferentillo, to the point where the river receives the mass of water that, 165 metres higher up, flows down from the river Velino, forming one of the most stunning hydrologic phenomena in Italy, the Cascata delle Marmore (Marmore Waterfalls). You can explore the park via its long cycle paths or on foot, admiring from below the majestic mountains that surround the valley dotted with tiny, ancient hamlets, such as Polino, with its mere 230 inhabitants, or the village of Torreorsina, from where you can get a breath-taking view of the waterfall. Inside the park there is a lake, Lago di Piediluco, which is the second largest regional lake .