Principality of Sealand, Artificial island with military platform in North Sea near Harwich, United Kingdom.
The Principality of Sealand is a former military platform made of steel and concrete rising on two hollow towers about 6 miles (10 kilometers) off the coast of Harwich in open water. The construction stands on legs roughly 60 feet (18 meters) tall and supports a deck the size of two tennis courts, surrounded by wind and waves.
The British Navy built this station in 1942 as HM Fort Roughs, an anti-aircraft position to defend the Thames Estuary against German bombers during World War II. After the war ended the military abandoned the site, which was then occupied by private individuals in 1967.
Since 1967 the platform has operated with its own flag, stamps, and titles of nobility granted to supporters worldwide. The small community considers itself an independent state and maintains ceremonies and traditions that visitors can witness during a stay.
The site lies in open water and can only be reached by boat, with crossings heavily dependent on weather and sea conditions. Anyone planning a visit should prepare for seasickness and unstable conditions, as the platform has no sheltered landing points.
A British court ruled in 1968 that the structure lies beyond national territorial waters, enabling claims of sovereignty. Since then there have been occupation attempts and even an armed incident recorded as a coup attempt in its history.
Location: Harwich
Inception: September 2, 1967
Founders: Paddy Roy Bates
Website: https://sealandgov.org
GPS coordinates: 51.89444,1.48250
Latest update: December 2, 2025 21:27
This collection brings together underground military sites, strategic bunkers, and highly secured installations across the world. Many of these places were built during the Cold War, when nuclear threats pushed governments to create protected command centers deep under mountains or in remote areas. Some remain active today, serving national security purposes, while others have been decommissioned but preserve their massive concrete structures and tunnels. Though their existence is known from public sources, access remains strictly forbidden. The sites include the Raven Rock Mountain Complex in Pennsylvania, carved deep into the Appalachian Mountains with tunnels stretching for miles through solid rock, and the Cheyenne Mountain Space Force Station in Colorado, where rooms rest on massive springs inside the Rocky Mountains to absorb shocks from potential attacks. In Russia, the Skalisty submarine base serves nuclear submarines through underground piers carved directly into rock along the Barents Sea. RAF Menwith Hill in North Yorkshire spreads across a wide area marked by white geodesic domes that protect satellite antennas, while the Svalbard Global Seed Vault lies embedded in arctic permafrost, storing millions of plant seeds behind thick concrete walls. These places show how governments sought to protect command systems, military operations, and even biological reserves by building deep into mountains or along remote coastlines, creating installations that remain largely hidden from public view.
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