The ancient Nahar, Italic name for the River Nera, has been at the centre of a mysterious legend for centuries, to confirm the importance the river has always had for the populations which reside along its banks.

The most famous of these legends recounts that the valley was infested by the mephitic miasma of a dragon, until two hermits, Felice and his son Mauro, arrived here from Syria to retire to a contemplative life in a cave close to Castel S. Felice. Thanks to the intervention of the two anchorites the dragon was defeated and the population was freed from the nefarious presence. It is probably one of the myths used to describe the foundation of the valley which, in fantastical forms, hands down the memory of the reclamation of the valley through the control of the river water.

A visit to the church of San Felice, in Castel S. Felice, is a must. The Romanesque façade presents a version of the tale admirably sculpted in bas relief below the rose window. The entire valley is set among steep slopes, often formed by high overhanging crags, by contorted and tormented limestone stratifications, large canals and pinnacles. It opens out in only some areas, and the slopes become gentler and the valley bottom becomes large and carpeted by fields and cultivated meadows. At times the flowing well-oxygenated water takes on the appearance of rapids, foaming among large rocks which have precipitated from the escarpments. This section of the river is the ideal environment for many animal species including the Brown trout, the Dipper and the Apennine frog to name but a few.

The River Nera rises inside the National Park of Mount Sibillini, at Castelsantangelo (Visso). Along its mountain course it has generated the deep valley called Valnerina, which man has shaped with a landscape of perched towers, bridges and villages.