On October 9, 1963, at precisely 10:39 p.m., a massive section of Mount Toc collapsed into the reservoir of the Vajont Dam in the Italian Dolomites. This sudden landslide triggered a massive wave that surged over the dam’s crest and swept through the valley in minutes, killing approximately 2,000 people. The dam itself, however, did not collapse. It was a double-curvature arch dam, a type of structure designed to withstand immense forces by curving both horizontally and vertically. The Vajont Dam, constructed between 1956 and 1960, stood 262 meters high and was located about 100 kilometers north of Venice. Despite the catastrophic wave, the dam’s structure remained intact and still stands today, though it is no longer in use. Geologists had warned about the instability of Mount Toc as early as the 1950s, but these concerns were largely ignored. In 1948, a report by geologist Giorgio Dal Piaz highlighted areas of debris with uncertain stability. Then, in 1959, Edoardo Semenza identified signs of ancient landslides on the mountain’s slope, suggesting the possibility of a massive rockslide. As the reservoir began to fill in 1960, these fears were confirmed when a large crack, shaped like an "M," appeared on the mountain. This crack expanded over time, and in November 1960, a significant landslide occurred. Engineers recognized the risk and built a diversion tunnel to prepare for future events, but they continued filling the reservoir. The summer of 1963 brought abnormally heavy rains, raising the reservoir level to nearly 250 meters—30 meters above the recommended depth. Only 15 meters of concrete separated the lake from overflowing. Meanwhile, the mountain’s slope continued to shift, with ground displacement reaching up to 3.5 centimeters per day. Despite these clear warnings, the mayors of Erto and Casso, two villages upstream, had conflicting responses. The mayor of Erto called for an evacuation, but few residents heeded the warning. In contrast, the mayor of Casso ordered a full evacuation and issued a notice about the potential landslide risk. However, the operating company, SADE, dismissed these concerns, claiming the area was not threatened and that the reservoir was closely monitored. On October 9, 1963, a massive 270 million cubic meters of rock—comparable to several hundred football stadiums stacked—slid into the reservoir in a matter of seconds. This caused a colossal wave that surged over the dam and fell 250 meters into the valley, devastating the peaceful villages in the Piave Valley. Longarone, the most affected village, was nearly erased from the map. Most of the victims were from this village, which still exists today, overshadowed by the dam that withstood the disaster. In the aftermath, public debate divided into two camps: one arguing it was a case of force majeure, or unavoidable natural disaster, and the other emphasizing human error in ignoring early warnings. A trial in 1968, held in L'Aquila, resulted in light sentences for SADE engineers, with most acquitted due to insufficient evidence. It took decades for legal proceedings to conclude, with financial responsibility eventually being assigned to ENEL and private entities in the 1990s. In 2008, UNESCO cited the disaster as a case study in the consequences of engineering and geological misjudgment. Today, the Vajont Dam remains standing, a silent witness to the tragedy that unfolded when blind trust in unheeded warnings led to one of Europe’s deadliest engineering disasters.