The wave wiped several villages out of existence, causing a level of destruction previously unseen in peacetime.

In the immediate aftermath, it seemed as though there could be only one possible cause.

The Viont Dam, one of the tallest dams in the world, must surely have clapped.

In fact, despite the incomparable destruction further down the river valley, the Viont Dam stood almost entirely intact.

The idea for the Viont Dam had first been suggested in the 1920s.

As Italy industrialized, the need for electric power was growing.

Constructing a hydroelectric dam would be one way to meet that need.

The project, however, faced numerous delays, not least those caused by the advent of World War II.

Once peace returned to Europe in 1945, the project was picked up once again, and serious work towards realizing it began.

The first step in the process was to survey the chosen site, a narrow, steep-sided section of the Viont River Valley near the base of Montauk.

These surveys were carried out by the Adriatic Electric Company, a government-backed company responsible for construction of the dam.

Their analysis of the geology of the area determined that it was stable enough for construction to go ahead.

Work began in 1957, but there were a number of setbacks.

As workers tried to complete new roads leading to and from the dam, they were hampered by unexpected ground movement.

Independent experts were brought in to conduct assessments, and warned that the whole mountainside was unstable.

This fact was driven home when a landslide at the nearby Pontessi Dam created a massive wave that overtopped the dam, swamped a power plant, and killed a construction worker in 1959.

The history of landslides in the area was common knowledge to local residents.

Some of them even referred to Montauk as the Mountain that Walks, because of how often it moved.

The Adriatic Electric Company, however, was reluctant to abandon or scale back the project, which was, after all, a prestigious piece of civil engineering.

Their own studies contradicted those provided by independent experts, and concluded that the dam would be safe so long as it was carefully managed.

Journalists who drew any connection between landslides and earth movements in the area and the safety of the Vyont Dam were, on some occasions, sued by the government, and soon fell silent.

By the 4th of November 1960, construction was mostly complete, and the Adriatic Electric Company had begun filling the reservoir behind the dam.

As the water level rose, a significant landslide took place, with a huge quantity of rock and soil crashing down into the growing lake.

The resultant wave did not overtop the dam, but was alarming enough to prompt the Adriatic Electric Company to carry out more research.

The company put its engineers to work constructing models of the dam and the valley to simulate what might happen in the event of another landslide.

They used the speed and size of the 1960 slide as a starting point, and carried out a barrage of tests, ultimately concluding that the dam would be safe so long as it was not filled above a height of 700 metres, or 2,297 feet.

In 1963, after months of rain, another landslide appeared imminent, with trees and rocks crumbling into the lake.

The mayor of the lakeside village of Erta was so worried that he called for an evacuation.

Engineers at the dam, however, were unconcerned.

In accordance with the research conducted by the Adriatic Electric Company, the water level in the reservoir had been lowered to the point that they were certain no landslide could possibly cause a wave that would overtop the dam.

So confident were they in this assessment that some workers gathered on top of the dam to watch the landslide and ensuing wave.

When it finally came at 10.39pm, those working at the dam were among the first to die.

Attractive land the size of a small town plunged into the lake over the course of just 45 seconds.

Much faster than anticipated.

This both raised the water level and created a massive wave that spread out in all directions.

This wave overtopped the dam and swept on down the river valley in a solid wall of water the height of a 70-storey building.

The waves which spread out across the lake destroyed the village of Erta, which had only been partially evacuated.

The wave that flowed down the river valley swallowed up farms, houses and numerous settlements as it went.

The villages of Longoroni, Birago, Rivalta, Villanova and Fe were all wiped off the map.

The wave swept away trees, rocks, buildings, cars and people, leaving behind nothing but a flat plain of mud.

As it entered the narrow valley, the wave pushed ahead of it a wall of air that crashed into anything in its path with the power of a hurricane.

Windows broke, people were bowled off their feet, cars picked up and thrown and houses flattened.

Following seconds behind this destructive storm was the wave itself, a churning mass of water and debris that proved deadly to almost anyone caught up in it.

One survivor, Michaela Coletti, a child at the time, related her experience of the disaster.

She came into my room and said she was going to close all the shutters because the storm was coming.

At exactly the same moment, all the lights went out and I heard a sound impossible to describe properly.

The closest thing I've ever heard to it is the sound of metal shop shutters rolling down, crashing shut, but this was a million, a billion times worse.

I felt my bed collapsing, as if there was a hole opening up beneath me and an irresistible force dragging me out.

I couldn't do anything.

I had no idea what was happening.

When they pulled me out, there was a popping sound like when you open a bottle, and someone said, We found another old one.

I was just twelve, but I was covered in mud and completely black and must have looked like an old woman.

Michaela was among a lucky few to survive.

In the majority of the flood-hit towns, around 80% of residents were killed within the first 15 minutes of the disaster.

With bodies buried by debris or washed miles down river, an exact death toll is difficult to determine, but by most estimates the flood killed at least 2,000 people.

Though the Italian army was dispatched to attempt the rescue operation, the most they were able to do in many cases was to recover and later rest the bodies of those killed.

In the aftermath of the disaster, the government insisted that the flood had been an unavoidable natural disaster.

Indeed, it had been caused by months of rain and a landslide, both conventionally natural disasters.

The fact that the dam had been situated in such an ill-advised location was barely acknowledged.

Because it was a natural disaster, the government was able to pay a lesser amount of compensation to many survivors, or outright deny compensation claims in some cases.

The village of Vient was built to provide housing for many of the survivors, although some chose to return to the land where their houses had stood before the flood.

The government discouraged but allowed this, and turned its attention to industrializing the area as much as possible in an attempt to aid its economic recovery.

For some years, the Vient Dam disaster was regarded as a regrettable accident in the route of progress, the result of an uncontrollable, natural phenomena.

It was only over the course of many years that the role played by the government and by those working on the dam project was acknowledged.

Now the dam is considered an example of a grave error of judgment, a project pursued in spite of numerous warning signs.

The dam remains in place.

Though the uppermost portion of the structure was damaged by the wave, it remained largely intact.

It has since been repaired, but is no longer used to provide hydroelectric power.

Instead, it is a tourist attraction and a memorial.

It is still one of the tallest dams in the world, but it holds no water, and instead serves as a reminder of one of the most destructive and needless disasters in Italian history.