Never heard of this...must see. Gorgeous! Marmore Falls, the largest man-made waterfall in the world. Umbria, Italy. Cascata delle Marmore or more popularly known as Marmore’s Falls. Its source of water is the Velino River. This 165-meter man-made waterfall was created by the ancient Romans. It’s one of the tallest in Europe and the tallest man-made waterfall in the world. It is located 7.7 km from Terni, a provincial capital of the Italian region of Umbria.