Military installations around the world often embody a paradox: they are simultaneously highly visible and yet shrouded in secrecy. While society is aware of their existence, the precise activities and purposes of many bases remain tightly guarded, with official confirmations coming only decades later—if at all. Beyond the famous Area 51 lies a multitude of covert sites, many enveloped in mystery and fueled by speculation. Here, we delve into ten of these hidden military installations and uncover some of the secrets behind their secrecy.

Pine Gap (Australia)
Nestled in the remote Australian Outback, Pine Gap is a joint U.S.-Australian base established in the 1960s. Officially dubbed the “Joint Defense Space Research Facility,” it was originally used to monitor Soviet missiles during the Cold War. Today, it commands numerous spy satellites and supports surveillance operations primarily across Asia. Despite its prominence, the true scope of Pine Gap’s activities remains largely classified—even Australian prime ministers have been kept in the dark about its exact functions. Leaked documents from Edward Snowden revealed Pine Gap’s role in guiding targeted drone strikes during the War on Terror, but many details remain unknown.

Porton Down (United Kingdom)
Porton Down, officially the Defence Science and Technology Laboratory, has a long history dating back to 1916 as Britain’s principal chemical weapons testing site. Although the UK government asserts that offensive chemical and biological weapons research ended in the 1950s, the facility continues to study dangerous pathogens such as Ebola and anthrax, along with nerve agents—primarily to develop defenses against these threats. Its secretive nature and sensitive research have made it a focus of intrigue over the decades.

Area 6 (Nevada, USA)
While Area 51 captures much popular imagination, Area 6 sits just 12 miles away and is much less well-known. Unlike its neighbor, Area 6’s activities are less publicized but include having a mysterious landing strip visible even on Google Earth. The U.S. National Nuclear Security Administration states the area is used by the Department of Defense and Department of Homeland Security for sensor testing, including drones. Beyond this, though, what exactly takes place there remains classified.

Dugway Proving Ground (Utah, USA)
Covering an area nearly the size of Rhode Island, Dugway Proving Ground was established in 1942 for testing biological and chemical weapons. Like Porton Down, its declared mission includes researching countermeasures against such weapons. The vast desert facility supports Army Reserve and National Guard training and Air Force test flights. Some conspiracy theories dub Dugway "the new Area 51," reflecting public suspicion about the unknown activities inside.

Kapustin Yar (Russia)
Russia’s equivalent of Area 51, Kapustin Yar was a top-secret air base famous for launching Laika, the first living creature to orbit Earth. The Soviet government denied its existence until 1983, decades after it was built. Kapustin Yar has been the center of many alien conspiracy theories, including claims of underground labs conducting alien autopsies. Apart from space launches and low-yield nuclear tests, the base is largely subterranean, and the full scope of operations is only known to a select few.

South China Sea Bases (Spratly and Paracel Islands)
China’s extensive island-building projects in the South China Sea have created over 3,200 acres of new land housing numerous military installations. Equipped with radars, missile launchers, and military air facilities, these bases assert control over vital shipping lanes and resource-rich areas. Especially mysterious is China’s 2016 announcement of plans to establish a secretive underwater base 10,000 feet below the sea surface. Given their remote locations and robust defenses, the precise purposes and capabilities of these bases remain under speculation.

HAARP (Alaska, USA)
The High Frequency Active Auroral Research Program (HAARP) has become notorious for spawning myriad conspiracy theories since its inception. Originally run by the U.S. Air Force, Navy, University of Alaska Fairbanks, and DARPA, HAARP studied the ionosphere to improve communications and surveillance. However, false claims have circulated that it can control weather, cause earthquakes, or even manipulate minds. The most extreme conspiracy involved an attempted terrorist attack targeting HAARP, motivated by beliefs in its supernatural capabilities. Despite the rumors, HAARP’s research has focused on atmospheric science rather than weaponization.

Dulce Base (New Mexico, USA)
Perhaps one of the most legendary clandestine bases, Dulce Base is rumored to be an underground complex beneath the small town of Dulce, New Mexico. Since the late 1970s, allegations of alien collaboration and secret battles have circulated, sparked by reports of animal mutilations, alleged intercepted alien communications, and eyewitness testimony from former personnel. The U.S. government denies the existence of any facility there, and no concrete evidence has surfaced, keeping Dulce firmly in the realm of urban legend and speculation.

Raven Rock Mountain Complex (Pennsylvania, USA)
Known as “Site R” or the “Underground Pentagon,” Raven Rock is a vast command center carved into a mountain designed to house military leadership in the event of nuclear war or national disaster. Spanning a half-mile inland and downward, the complex includes its own power plant, reservoirs, fire and police departments, and accommodations for up to 2,000 personnel. Although its existence is public knowledge, the operations inside are classified to ensure continuity of government under catastrophic conditions.

Mount Yamantau and Mezhgorye (Ural Mountains, Russia)
Deep beneath the Ural Mountains lies Mount Yamantau, believed by U.S. intelligence to be home to one of Russia’s most secretive military complexes. Speculation suggests it functions as a hardened bunker akin to the American Cheyenne Mountain, serving as a nuclear command center or fallout shelter. The nearby closed city of Mezhgorye, home to about 17,000 people but absent from maps, serves the facility. Russian authorities have offered unconvincing explanations—such as mining or food storage—to explain the site’s purpose, heightening mystery and suspicion.

These ten military installations exemplify the shadowy intersection between national security, technology, and secrecy. While some serve overt strategic needs with transparency, many operate behind veils of silence to protect classified operations. Whether counterterrorism hubs, nuclear bunkers, or alleged alien laboratories, their hidden natures captivate public imagination and serve as reminders of the limits of our knowledge about global military endeavors.