Zarzalejo is a Spanish city in the autonomous region of Madrid.

Zarzalejo bordered to the north by the municipalities of Santa María de la Alameda and San Lorenzo del Escorial, in the south and east by Robledo de Chavela. The city lies at the foot of Machotas Mountains, which are part of the Sierra de Guadarrama.

Zarzalejo has an upper and a lower center. To the top there is the old town, around the bottom - built numerous chalets have been in recent years - called " La Estación " (the station ).