Of the more than 100 such lakes created between the hills and ridges surrounding Roșia Montană, several still exist today. The largest are equipped with sophisticated mechanisms—including cranes—for controlling the water. The control mechanisms, initially constructed of wood, were gradually replaced by metal cranes operated from a tower. The dams and water outlets are remarkable examples of engineering architecture. Water from the surrounding hills is collected behind the dam. At the base of the dams is a tunnel connected to a control tower. The tower, in turn, stands in the middle of the lake. Source: Rosia Montana UNESCO World Heritage Association