On this route we can enjoy some excellent views of the sierra that are little known and with a climb up a hill that is right next to the town of Collado Mediano. From its viewpoints you can enjoy landscapes that are not usually seen from this medium altitude. From the first viewpoint to the south we can see how the Guadarrama River basin opens up, and from the second to the north we can enjoy the peaks of Siete Picos, La Bola del Mundo and La Maliciosa. It can be accessed in different ways, perhaps the easiest to find is from the Plaza del Ayuntamiento, which we leave on our left to ascend towards the reservoirs along the Calle de la Ermita and then along the Calle de la Cobañera. After a climb we leave the town centre and the tarmac gives way to a dirt track that leaves one of the tanks on the right and a few metres further on the second one. You soon reach the pine forest and after a few minutes, on your right you will see a small turn-off to the Mirador de la Cobañera viewpoint. The viewpoint is formed by some granite rock crags that offer a good panoramic view of the town centre of Collado Mediano. Return to the dirt track and continue ascending through pine trees along this obvious path, ignoring the first turning to the right. We continue until we come to a sign indicating "Cerro del Castillo" to our right, ignoring the path to the left. We take this path, crossing a fence that prohibits the passage of vehicles, and begin to ascend between rockroses and pines. At the next crossroads there is a sign indicating "Casa Forestal" on the right and "Cerro del Castillo" on the left. We take the latter path, which climbs along a fairly wide dirt track that we will not leave for the time being, despite the paths on our right. Although these paths also climb the Cerro del Castillo, they are steeper, narrower and harder. The path makes a few sharp bends, after which we will have to take the narrow, steep path to our right. This rather steep and sometimes eroded path will take us to the highest point of our route: the Cerro del Castillo. When we reach the top, we can admire the fantastic view from a balcony-like viewpoint, which we have deservedly earned.