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. The range runs southwest - northeast, extending into the province of Madrid to the south, and towards the provinces of Ávila and Segovia to the north.