Nestled in the Sologne region of France, the Nançay Radio Astronomy Observatory is home to two massive metal structures: a 200-meter-long, steerable planar mirror and a 300-meter-wide spherical mirror. These structures form the Grand Radiotelescope, one of the largest single-dish radio telescopes in the world. The site was selected in 1952 for its flat landscape, low population density, and relative closeness to Paris, which helped minimize radio interference from human activity. The observatory was officially opened on October 21, 1956, by René Billères, then Minister of National Education, Youth, and Sports, and later, in 1965, the Decimetric Radiotelescope was inaugurated by President Charles de Gaulle and Minister Christian Fouchet. The telescope’s design is both precise and innovative. The steerable mirror is made up of 10 separate panels, each measuring 20 meters by 40 meters, allowing the telescope to be directed toward different parts of the sky. The spherical mirror is crafted with extreme accuracy, deviating no more than 5 millimeters from a perfect sphere with a radius of 560 meters. When radio waves from space reach the telescope, they are reflected toward a focal cart at the center. This cart moves along an 80-meter railway track to track celestial objects as they pass overhead, allowing the telescope to collect and analyze the signals. With a collecting surface of 8,000 square meters, the telescope is equivalent in sensitivity to a parabola 94 meters in diameter. At the time of its inauguration, it was the largest antenna in the world dedicated solely to astronomy. It detects radio waves emitted by hydrogen gas in space, specifically in the frequency range of 1 to 3.5 gigahertz. This capability allows scientists to study a wide range of cosmic phenomena, including galaxies, stars, comets, and pulsars. The observatory has also contributed to the search for extraterrestrial intelligence (SETI) and has studied four stars known to host giant planets. The Nançay Radio Astronomy Observatory continues to be a hub of scientific research and technological advancement. Since its initial commissioning, the site has undergone several upgrades, including the installation of NenuFAR, a modern low-frequency radiotelescope designed to study radio waves from the early universe. Its location in the quiet countryside of Cher still ensures minimal radio interference, preserving the observatory's ability to detect the faintest signals from space.