Continental Auto buses (Línea Sierra Norte) depart from the Plaza Castilla Intercambiador station hourly, and the journey time is about 90 minutes. They operate between 6:15am and 11pm on weekdays and between 8am and 10:30pm on Saturday and Sunday. The last bus back to Madrid is at 8pm (tel. 91-314-57-55).
Driving, take the northerly N-1 highway, which leads straight through Buitrago del Lozoya on its way to Burgos. Once clear of the city, you should get there easily in an hour.
The town hall in Buitrago (tel. 91-868-00-56) gives useful local information.
Note: This information was accurate when it was published, but can change without notice. Please be sure to confirm all rates and details directly with the companies in question before planning your trip.