The Arecibo radio telescope, once the world's largest until 2016, collapsed on December 1, 2020, following the rupture of several support cables. The massive 900-ton receiving platform fell onto the telescope's main dish without causing injuries, as the area had been evacuated beforehand. The National Science Foundation (NSF), which oversees the facility, has decided against rebuilding the telescope, which would have cost around $400 million. Instead, the site has been repurposed into a STEM educational center since 2022. Located in a tropical valley in Puerto Rico, the Arecibo telescope operated from 1963 until its collapse. It featured a 305-meter-diameter metal mirror carved directly into the natural rock formations of a Caribbean island. Unlike traditional telescopes that rotate to track celestial objects, Arecibo's reflective surface remained fixed, while a suspended receiving platform 137 meters above the dish moved to capture signals from space. This design, supported by a complex network of steel cables, enabled groundbreaking discoveries, including the first detection of an exoplanet and evidence supporting the existence of gravitational waves from a binary pulsar. The collapse was the result of a series of structural failures. An auxiliary cable broke in August 2020, creating a large hole in the main dish. Three months later, in November 2020, a main support cable snapped, prompting the NSF to announce the telescope's permanent decommissioning due to safety concerns. On December 1, the receiving platform detached from its remaining cables, plummeting 152 meters to crash onto the dish. The impact destroyed both the fixed antenna and the suspended platform. The event was captured by surveillance drones, and images of the collapse spread globally. The loss of Arecibo has weakened NASA's ability to monitor near-Earth asteroids, as the telescope was a key tool for radar observations of their trajectories. The NSF has ruled out rebuilding the telescope, citing the high cost and shifting budget priorities. Since 2022, the site has been transformed into a STEM educational center, aiming to inspire future scientists. The collapse marked the end of an era in astronomy, as the telescope had played a crucial role in fundamental astrophysics research and stood as a symbol of scientific achievement.