The 1717 metres of altitude forming Castro Valnera turn this place into the most emblematic climb of Pas world and the most relevant peak in the Cantabrian Range on its east side. It is also a historical and artistic symbol.

What we propose here is the mountain route most representative of the region. The interesting climb has different feaures: ethnographic, cultural, panoramic and geomorphological. From a sports point of view it is a fairly easy climb, without particularly exposed passes and with an unimportant slope of about 400m from Portillo de Lunada.

The most common journey starts from Collado, next to the road to Espinosa de los Monteros from Miera valley. Here we can still see, although not well-preserved, remainders of the ancient pathway communicating Miera valley with Alto de Trueba in Burgos.

The pathway dates from before 1802 and 1803, when it was documented by Rubio Marcos from the Municipal Archive of Espinosa de Los Monteros, and apparently when it was improved.

Once passed the rocks of Canto Las Corvas and Pico La Miel, we go along the border between Cantabria and Burgos and descend to Canto de La Piluca through a small, well-defined trail.

The final ascend to the peak takes us to Collado de Pirulera, next to the depression of Torcaverosa. We should do this route on sunny days, in order to avoid getting lost in a karstified area that is very dangerous under adverse conditions. We can go back through the same path towards Lunada or through Peña del Cuervo to Estacas de Trueba pass, on the other side of the mass.

Along this hike we can enjoy a magnificent landscape above the Pas and Pisueña valleys, and we can see the structure of the region towards the west, with rivers, hills and depressions.

The perspective from this vantage point makes any other in these valleys seem insignificant. Everything seems smaller, less important. Everything seems to be: a succession of more or less sloped formations of valleys, pastures, forests and rivers.

Furthermore, if we go with the idea of learning, we can appreciate the different origins of the mass morphology: glacier, limestone, karstification...