Carucedo marks the beginning of the ascent towards Las Médulas, a landscape formed by red and rugged clayey mountains that emerge amidst green vegetation, declared a World Heritage Site by UNESCO in 1997.Las Médulas are a work of Roman engineering, who exploited the numerous, rich gold mines found in the area. For this purpose they used a complex system of channels that would bring water from the Aquilano mountains, more than 15 km away. The Romans would drill galleries into the mountain (some of which still stand), flood them, and wait for the water to cause the mountain to collapse, crumbling down towards the washeries, where they would examine the fragments searching for gold. These washeries became lakes with the passage of time, such as the lake of Pozo Sumido, or Redondo lake. In total, they extracted about 240 million cubic metres of soil for mineral separation, that yielded an estimate of 800,000 kilograms of gold. This mining procedure, along with the vegetation and natural erosion, managed to create the breathtaking scenery that we see today.