Cascata delle Marmore, Terni: The Cascata delle Marmore is a man-made waterfall created by the Romans near the town of Terni in Umbria, central Italy. It's 165 meters high with three separate falls, the biggest of which is 83 meters. The water, which originally comes from the River Velino, normally flows into a hydroelectric power plant, but at certain times every day it is diverted down the falls, to the delight of paying tourists.