The area spans 233 hectares and is part of the sedimentary cover of the Argentera Crystalline Massif, consisting of limestone and dolomite formations that allows several typical Mediterranean species (plants and animals) to live in the heart of the Alps. Their presence there is favoured by the unique microclimate, created by its southern exposure, and a morphology that protects it from the main local winds. The most important of these is a plant, the Phoenicean juniper. The presence of this shrub in the area marks two Italian firsts: the population survives at the highest known altitude and grows the farthest north from those of the nearby Stura Valley. Another “gem” of the Reserve is the endemic primrose of Allionii which, starting from February, punctuates the grey limestone walls of the Rocca San Giovanni and Monte Saben with its red flowers.

Due to the high naturalistic value of the reserve, the fragility of the environment and the species that live in it, visitors are only admitted along a marked ring path, which proves rather challenging due to the high slope. Instead, the Butterfly Trail that develops on the southern border of the protected area is extremely easy. The itinerary takes you to the Valdieri Archaeological Park and leads to an area of limestone quarry for cement not used since the 90s. The site is home to the beautiful Papilio alexanor, a Mediterranean butterfly, confined to a few run-down stations in the Alps, where it lives in close association with the Ptychotis saxifraga, an Umbellifera plant that feeds the caterpillars.