The Puerto del Escudo (Pass of the Shield) is a mountain pass at 1,011 meters elevation located in the valley of Luena, to the east of the Sierra del Escudo mountain range and on the boundary between Cantabria and Castile (province of Burgos) in Spain. The source of the Magdalena or is located there. It has been one of the main access routes from the coast to the interior plateau crossing the Cantabrian Mountains. At the moment the highway runs over it and is well known for its steep inclines on its Cantabrian slope that can be up to 15%, causing a difficult transit for heavy vehicles. This characteristic and its altitude result in the relatively frequent closing of the pass when there is heavy snow in the winter.