The Cascata delle Marmore or Marmore Falls is a man-made waterfall created by the ancient Romans. Its total height is 165 m, making it the tallest man-made waterfall in the world. Of its 3 sections, the top one is the tallest, at 83 m.
It is located 7.7 km from Terni, a provincial capital of the Italian region of Umbria.
Its source is a portion of the waters of the river Velino, after flowing through Piediluco lake near the community of Marmore. It pours into the valley below formed by the river Nera. Its flow is turned on and off according to a published schedule, to satisfy the needs of tourists and the power company alike. Tourists try to be there the moment the gates are opened to see the powerful rush of water.