If you want to base yourself in the mountains for a while you’d do best to head for Cercedilla. Alternatively, over to the east, there is Manzanares el Real, with its odd medieval castle and reservoir-side setting.
In the shadow of the mountains to the north lies the Valle de Lozoya. At the western end are the village of Rascafría and the nearby Benedictine monastery of El Paular, and to the east the old fortified town of Buitrago with a medieval core and small Picasso museum.
If you're planning a trip to Spain, don't miss our Spain itineraries and information on how to get there.