Somosierra is a mountain pass in the Sierra de Guadarrama

Sierra de Guadarrama

The Sierra de Guadarrama is a mountain range forming the main eastern section of the Sistema Central, the system of mountain ranges at the centre of the Iberian Peninsula. It is located between the Sierra de Gredos in the province of Ávila, and Sierra de Ayllón in the province of Guadalajara...

 north of Madrid

Madrid

Madrid is the capital and largest city of Spain. The population of the city is roughly 3.3 million and the entire population of the Madrid metropolitan area is calculated to be 6.271 million. It is the third largest city in the European Union, after London and Berlin, and its metropolitan...

 in Spain. It connects the north of the Community of Madrid with the east of the province of Segovia

Segovia (province)

Segovia is a province of central/northern Spain, in the southern part of the autonomous community of Castile and León. It is bordered by the provinces of Burgos, Soria, Guadalajara, Madrid, Ávila, and Valladolid....

. Just south of the pass is the municipality of Somosierra with a population of 116.

It has an altitude of 1,434 metres and is crossed by the A-1 (E5) road through a short tunnel; there is also a 3,895 metres long rail tunnel. Near the summit the Spanish authorities provide an unmonitored rest stop aimed at Arab migrant workers driving to France, to discourage them from simply stopping at the side of the road.

The road was originally a track opened up by Napoleon

Napoleon I of France

Napoleon Bonaparte was a French military and political leader during the latter stages of the French Revolution.As Napoleon I, he was Emperor of the French from 1804 to 1815...

 to provide a direct route to Madrid. In 1808 this led to the Battle of Somosierra

Battle of Somosierra

The Battle of Somosierra occurred November 30, 1808 in the Peninsular War, when a French army under Napoleon I forced a passage through the Sierra de Guadarrama shielding Madrid....

between French-Polish and Spanish forces.