Miraflores to Bustarviejo via Navalafuente
This is a fairly easy route of about 13k with not much in the way of ascent it should take about 3 hours. The path is easy and clear, actually it is what they call here a “Vía Pecuaria” or “Drovers trail”, it is also a good cycling track. Whilst not too demanding it does provide some good views of the surrounding mountains 
and there is always a good chance of seeing some of the eagles that nest nearby. I especially like this route in the Spring when the whole area is awash with wild flowers. It is also a great way of burning off the excesses of the night before without giving yourself a heart attack.
Start at the old Station in Miraflores de la Sierra (at the bottom of town), from the station turn left along the tracks for about a couple of hundred metres and take the path that goes up the right hand side of the tunnel. At the top of the tunnel go through the wire “gate” and turn left and after a few hundred metres you arrive at what can loosely called a cross roads. The main path is clear and straight ahead.
After just over 3k (about 50 minutes) you cross a small bridge over the railway and the path swings around to the left. Carry on for another 15 minutes (4.5k) and you reach a turning to the right which heads down to a small town called Navalfuente (about 30-40 minutes if you want to head there), Don’t take this carry straight on the main track.
A little further on about another 15 minutes (5k) there is a smaller path off to the left crossing back over the railway line on a small bridge. Here you have a choice:
Cross the bridge and you follow a small path cutting across the corner of the mountain (note this is a small path not a track). The path is fairly clear and easy to follow but does involve a little bit of climbing. The path cuts the corner of the mountain and then drops you back down the other side through a wood where it rejoins the main track (see below). From my point of view I prefer this option as it adds some variety (and better views).
The main track continues on curving around the mountain. Eventually crossing back across the railway and heading directly towards Bustarviejo (the option above rejoins the main path about half a kilometer after it crosses the railway). 
After about 3 hours you reach Bustarviejo, the village centre is off to the right where there is a regular bus service ( number 725) back to Miraflores.
Another alternative is when you reach Bustarviejo instead of turning right into the village you go left and skirt around the back of some industrial units where the track continues around the other side of the mountain back to Miraflores about another 2 hours. But more of this another day.