OverviewThis is the easiest route to the summit of Alto de las Guarramillas. Just a 10 km hike to get there and back to the parking lot. An easy hike, for sure, available to most people with a basic physical training. All you have to do is walk uphill, following a cement road to the summit. About sixty minutes to reach to the top, make it somewhere between two and three hours (obviously depending on your speed). A nice walk with (weather allowing) great views of the area around the mountain. Including Peñalara and La Maliciosa
Getting ThereThe trailhead for this route is the Puerto de Navacerrada, a mountain pass placed northwest of Madrid and 1860 meters above sea level. There's a (not too big) ski resort up there, with skilifts based on the mountain pass and going up towards the slopes of Siete Picos and Bola del Mundo. Obviously, a ski resort means buildings, bars, restaurants and so on. A good number of facilities allowing you to buy food or drinks but taking away most of the charm of the landscape.
By car:Puerto de Navacerrada is 64 km away from Madrid, driving northwest. The best driving option is to take the A6 motorway for 43 km, up to exit 39 (signposted as “Villalba/Puerto de Navacerrada”). Leave the motorway and take road M-601 (grossly northwards) to Navacerrada (about 13 km to go) and Puerto de Navacerrada (an additional 7 km, making 20 km from the motorway).
Another option would be the M-607 highway to Colmenar Viejo, continuing afterwards to Cerceda and Navacerrada to enter there road M-601 to Puerto de Navacerrada. This second option offers a better landscape and might be helpful in case of heavy traffic congestion in the A6. If you are coming from the north, drive to Segovia and take road CL-601 towards La Granja and Puerto de Navacerrada.
When you reach the Puerto de Navacerrada, the biggest car park is placed east of the mountain pass(where the road to "Puerto de Cotos" starts)
By train:The puerto de Navacerrada is also reached by an old mountain train departing from Cercedilla. If you choose this option, you would have to take a train to Cercedilla (line C-8b) at Atocha Railway Station (Madrid) and connect to the trains to Puerto de Navacerrada.
By bus:Buses to Cercedilla can be caught (lines 684 and 684A) at the Moncloa underground station (Madrid), allowing for connections with the Puerto de Navacerrada as they stop by the railway station when they reach Cercedilla. There are also buses to Puerto de Navacerrada (line 691) leaving from Moncloa.
By plane:The closest major airport stands at Madrid-Barajas.
Route DescriptionYour starting reference is the lower station of the chairlift leading east of the mountain pass. Look (it's easy) for that station and you will find by its side the beginning of a cement road leading uphill. Follow it, it winds quite a lot around the mountain but if you follow that cement road it will take you to Alto de Dos Castillas (2179 m, upper station of the chairlift) in 50 to 60 minutes. Should you prefer to walk uphill, cross-country, and avoid the dirt road, that's also possible. Just leave the road and climb the grassy (and bushy) slopes east of the Puerto de Navacerrada following the chairlift.
When you get to Alto de Dos Castillas you will have to follow the cement road eastwards to reach the summit of the Bola del Mundo (2266 m, also known as Alto de las Guarramillas), easily identified by its huge TV antennas. Getting there will take 15 to 20 minutes.
The way back to Puerto de Navacerrada will be the same described in these lines, just walk all the way down to the ski resort (either via cement road or direct downhill walking).