The southern Swedish island of Öja was a strategic location in the Baltic Sea when it came to the country’s shoreline defense. Fearing a Russian invasion by sea during the Cold War, the military decided to replace many of the old shore defenses with a new system: the ERSTA artillery battery. In the 1970s, the military built six of these systems, with one stationed in the village of Landsort on Öja. Today, the Landsort battery is the only one that remains.

At the time, it was among the most advanced artillery systems in the world, and is still hard to top in terms of accuracy, protection, and defense. Its cannon, which could fire with great precision, was protected by a large dome and its operations facility was hidden deep in a rock. It was able to operate for a month without being resupplied while withstanding chemical, biological, radiological, and nuclear attacks following CBRN defense protocol. 

The artillery battery stood guard until the turn of the century, when the Swedish military changed its policy from focusing on defense from invasions to operational defense, strike teams, and mobility. All of the ERSTA batteries have been decommissioned and dismantled except for this one in Landsort. It lies, nearly hidden among the brush on the island.