Electric railway of the Guadarrama Activity · Cercedilla, Cuenca del Guadarrama, Madrid Image of Cercedilla, not of the place itself. Inaugurated on 12 July 1923 in the presence of Alfonso XIII, it climbs from Cercedilla to Cotos over a height difference of 719 metres; it is the only metre-gauge line on the Adif network and is still electrified at 1,500 volts direct current. Photo: Smiley.toerist (CC BY-SA 4.0) What to see and do in Cercedilla