At the time it was built, the Vajont Dam was the tallest in the world. Constructed in the late 1950s to boost Italy’s postwar economy, the roughly 850-foot-tall structure was an impressive feat of engineering. But its initial glory took a tragic turn a few short years later during one of the worst anthropogenic environmental disasters of its era.

On October 9, 1963, at 10:39 p.m., over 340 million cubic yards of rock toppled from the top of Monte Toc at up to 68 miles per hour. The debris tumbled into the dam’s water reservoir, producing an enormous wave. This megatsunami caused the water to surge to catastrophic proportions. It crashed over the barricade, destroying several villages in the valley and killing about 2,000 people. Entire families perished. Longarone, the largest village, was hit the hardest.

Surprisingly, the dam remained mostly undamaged, despite the fact the wave pushed an air pocket ahead of it that had a force twice as powerful as the Hiroshima bomb explosion. The colossal structure still towered above the land, though the valley below was reduced to a stretch of muddy ruins. The few survivors were relocated to other villages.

In the aftermath of the disaster, the government and engineers behind the dam’s construction were heavily criticized for building the barricade in the first place. Locals, already aware of the region’s seismic shifts and geologic instability, had warned of possible disasters.

Now, the dam stands as an odd memorial to the tragedy. The villages were rebuilt, and nature has spent the years slowly fading and healing the scars the flood left on the land in its wake. Some survivors who remained in the area view the dam as a way to keep the legacies of their lost loved ones alive and ensure the devastation is never forgotten.