Natural Area of the Riera de Muntanyola Nature · Castellterçol, Moianès, Barcelona Image of Castellterçol, not of the place itself. The area of the riera de Muntanyola, in the Moianès, was protected by the PEIN through Decree 328/1992, an extension completed by Decree 166/2010. It extends between 400 and 1,000 metres altitude, over limestone and marl relief, and preserves a good representation of holm-oak forest with elements of submediterranean vegetation that are rare in the area. Among its fauna, rich in carnivores, notable are the fox and the genet, the short-toed eagle among the birds of prey, and the otter and the native river crayfish in the watercourse, threatened by invasive species such as the American mink and the American crayfish. Photo: Enfo (CC BY-SA 3.0) What to see and do in Castellterçol