The Sierra of Demanda is one of the most beautiful wild areas in Burgos. It is located in the Southeast of the province, sorrounded by three mountain masses to the Northwest of the Sistema Ibérico massif: the Sierras of San Millán, Mencilla and Neila. In Sierra Neila there are glacial lagoons bordered by splendid specimens of the "Pinus sylvestrus". The Demanda area is of great geomorphological interest. There are traces of glaciation on its peaks and old mountain masses where can be found Paleozoic, Triassic and Jurassic elements.

This natural setting is also a vegetal paradise. The flora includes beech groves, badgers, holly trees, yews and specimens of the "Pinus sylvestrus" and "Querais Pyrenaica".

The fauna is also worthy of note. The woods are inhabited by wolfs, roe deers, deers, badgers, wildcats, otters, royal eagles, snakes, goshawks, falcons and "Galemys pyrenaicus".

Apart from its biological diversity, this wild area offers ethnographic attractions. There are many villages filled with history and art. Worthy of note are the Romanesque portals of Vizcaíno, Pineda de la Sierra and Jaramillo de la Fuente; the Medieval monasteries and necropolis of Revenga, Cuyacabras, Cueva Andrés and La Cerca; and the forges of Barbadillo de Herreros and Huerta de Abajo. The works of popular architecture show an influence of the rooted transhumant customs of the area.

Access to this unique natural park is via Quintanar de la Sierra, from which a road through Sierra de Neila and Mancilla leads to La Demanda.