Somosierra is a mountain pass in the Sierra de Guadarrama north of Madrid in Spain. It connects the north of the Community of Madrid with the east of the province of Segovia. Just south of the pass is the municipality of Somosierra with a population of 77.
It has an altitude of 1,434 metres (4,705 ft) and is crossed by the A-1 (E5) road through Túnel Juan Manuel Morón Garcia, a short twin-bore tunnel named in honour of a civil engineer who worked on the Spanish motorway network.[1] There is also a 3.9-kilometre-long (2.4 mi) rail tunnel.