The Marmore Waterfall is known for its 165 meter drop which offers an amazing sight set in a natural context.
In realty the Waterfall is the work of man and has controlled the flow of water over the course of two millennia.
The name Marmore derives from the calcium carbonate salts present on the rocks which are similar to white marble and form a particularly spongy limestone called pietra sponga.
The waterfall originates from the Velino River which is channeled near Lake Piediluco, near the village of Marmore and flows down until it drops into the Nera River below.
The Velino River flows along the Rieti valley carrying with it various sediments that over time deposit downstream forming a barrier.
In the course of geological eras, the limestone formations have produced the current difference in height between the Terni and Rieti basins, favouring the formation of Lake Velino and the swamping of much of the Rieti valley.
In 271 B.C., the Roman consul Manio Curio Dentato had a canal built (Cavo Curiano) to allow the stagnant waters to flow towards the natural drop of Marmore. In fact, from there the water overflowed in a disordered way directly into the Nera River.
The solution of the problem upstream created another one downstream as it was in concomitance with the overflowing of the Velino, the huge amount of water carried by the Nera directly threatened the inhabited centre of Terni. This was the reason for a dispute between the two towns of which the same Cicerone dealt with.
With the fall of the Western Roman Empire the maintenance of the canal ended. This led to a decrease in the flow of water and a progressive swamping of the Rieti plain.
Only in 1422, by the will of Pope Gregory XII, a new canal was built to restore the original flow of the river (Cavo Reatino or Gregoriano).
Subsequently, in 1545, Pope Paul III gave a mandate to Antonio da Sangallo the Younger to open another canal, the Cava Paolina. But this solution only partially managed to resolve the situation, so the original solution was adopted, expanding the Cava Curiana and building a bridge regulator, a sort of valve that would regulate the water flow.
The work was inaugurated in 1598 by Pope Clement VIII, and took the name of Cava Clementina.
However, this intervention did not resolve the flooding problem of the plain below and after two centuries, in 1787, by order of Pope Pius VI, the architect Andrea Vici worked directly on the drops of the waterfall giving them their current appearance and finally resolved most of the problems.
In the 19th century the waters of the Fall started to be used as a driving force. In 1896, the newly formed Steelworks of Terni fed their mechanisms exploiting 2 m³ of water from the Cavo Curiano.