Since we left Cangas de Onis we have been 18 kilometers enjoying the "Desfiladero de Los Beyos", in the vicinity of kilometer 131 of the N-625 road (Cangas de Onis-Riaño), once we have passed the Agüera bridge over the Sella river, we find a detour to the right indicated with a sign that says VIBOLI - CASIELLES. During the first kilometer we will cross a road excavated in the stone of the "Foz del Andamio", gorge formed by the river Viboli, until we reach the crossroads where the climb begins of 3 kilometers and 23 curves to save a difference of 380 meters. The road is narrow, with sharp curves, a lot of gravel, cows and their excrement everywhere, they make us be very attentive almost without being able to delight in the landscape, until we arrive to the "Collau Caleyu".