Green Bank, West Virginia, sits in a high valley in Pocahontas County, screened on every side by the Allegheny Mountains. When the National Radio Astronomy Observatory was founded in 1956, planners chose this valley specifically because the mountains blocked terrestrial radio noise - cars, broadcast stations, microwave links - from leaking in. The site was further protected when Congress and the FCC established the United States National Radio Quiet Zone in 1958, a 13,000-square-mile area centered on Green Bank within which radio emissions are restricted to keep the observatory's instruments quiet. Inside the zone, cell phone service is essentially nonexistent. Wi-Fi is limited. Even microwave ovens have to be shielded - the small leakage from a typical kitchen microwave is enough to register on the most sensitive telescopes.

The Robert C. Byrd Green Bank Telescope, completed in 2001 and named for the West Virginia senator who championed its funding, is the world's largest fully steerable radio telescope. Its dish measures 100 by 110 meters - more than two football fields wide. It can be pointed at any object in the sky above 5 degrees elevation and tracked across the heavens as Earth rotates. Its sensitivity allows it to detect radio signals so faint that they amount to less energy than a snowflake landing on a roof. The telescope succeeded the 300-foot transit telescope, which had been the world's largest moving telescope until November 15, 1988, when a single gusset plate inside one of its beam joints failed and the entire structure suddenly collapsed in the middle of the night. Nobody was injured. The Byrd telescope went up in its place, redesigned to avoid the same single-point failure.

Before the Byrd telescope, before the 300-footer, there was the Howard E. Tatel Radio Telescope - an 85-foot dish completed in 1959. Frank Drake used the Tatel in April 1960 for Project Ozma, the first systematic search for extraterrestrial intelligence using a radio telescope. He pointed the dish at Tau Ceti and Epsilon Eridani, two of the closest sun-like stars, and listened on a frequency near 1420 megahertz - the hydrogen line, which Drake reasoned any technological civilization would know about. Ozma ran for two months and found no convincing signals. The Tatel dish is still on the Green Bank campus, though it is no longer used for active astronomy. Drake went on to formulate the Drake Equation, which estimates the number of communicating civilizations that might exist in the galaxy. SETI as a scientific discipline traces its origins to that 85-foot dish in West Virginia.

For decades, Green Bank was operated as part of the National Radio Astronomy Observatory under contract with the National Science Foundation. In 2012, NSF recommended fully divesting from Green Bank by October 1, 2016, as part of a broader effort to direct scarce federal astronomy funds toward newer facilities. Rather than close, the observatory went independent. On October 1, 2016, the Green Bank Observatory became a stand-alone institution, retaining partial NSF funding, establishing private contracts to use the telescope's time, and forming a partnership with West Virginia University. The new model works, more or less. Astronomers from around the world buy telescope time. The Breakthrough Listen project, a privately funded modern SETI effort, has been a major customer. The observatory has survived a near-death experience and emerged with a more diversified funding base than it had under the NSF.

Green Bank attracts an unusual mix of visitors. Astronomers come for telescope time. Tourists come for the on-site Science Center, which offers tours of the campus and views of the dishes. People who suffer from electromagnetic hypersensitivity - a controversial condition in which sufferers report symptoms they attribute to ambient radio waves - have moved to Green Bank specifically for the quiet, forming a small expatriate community. Conspiracy theorists have long speculated about secret government activities at the observatory, fueled by its proximity to Sugar Grove Station, a former NSA listening post, and to the Greenbrier resort with its Cold War-era congressional bunker. The 2025 documentary Small Town Universe was filmed almost entirely at Green Bank. Captain America Brave New World used a fictionalized Green Bank as a location called Camp Echo One. The actual telescopes are stranger and more interesting than any of the stories about them.