I enjoyed this forum post by Alfredo on hiking in the Picos de Urbión in Soria.
“The Picos de Urbión is one of the most important sections of the Sistema Ibérico, the mountain range that crosses east to west through the north of the Iberian Peninsula. In this range we find the source of the Duero, one of Spain’s great rivers. The region is also a popular location for walkers and outdoor enthusiasts and is home to the magnificent glacial lake, the Laguna Negra, an inspirational place of the famous Spanish poet Antonio Machado. “