Los Argüellos is a Biosphere Reserve that is located in the north of the province of León, in the Autonomous Community of Castilla y León, bordering Asturias. It is formed by the municipalities of Vegacervera, Valdelugueros and Cármenes and is rich in caves, such as those of Valporquero, Llamazares and Barredo.
Also within the reserve are the Hoces de Vegacervera, a 500 meter deep and 15 meter wide gorge formed by the Torío River, and the old mines of La Profunda. There are also various remains of the Roman era, such as bridges and Roman roads.
The area is located in the central part of the Cantabrian Mountains with peaks of around 2,150 meters, surrounded by the mountain ranges Alto Bernesga a>, Redes and further away the Picos de Europa and the Montaña Palentina. Thanks to an extensive network of marked trails, Los Argüellos is excellent for hiking.