Reservoir of Picadas Nature · Navas del Rey, Sierra Oeste, Madrid Concrete gravity dam built in 1952 in a narrow gorge of the Alberche: 59 metres high and 145 long for a reservoir of barely 15 hm³ and 92 hectares, used for hydroelectric production, irrigation and water supply. Photo: Paconi (CC BY-SA 3.0) What to see and do in Navas del Rey