hike this weekend in the madrid sierra

proposed walk:
Saturday, September 19,
Puerto de Navacerrada-up Hollow Seven Peaks,
distance about 15 kms., trails and shaded paths with good views,
low degree of difficulty,
bring walking boots and  walking stick/s, a snack, eg a sandwich and a waterproof jacket
Approximate cost of travel, 7 euros.
Meeting point: Plaza de Castilla, next to the water tank of the Canal de Isabel II and subway exit, at 10:30 h.