Dutch group bunker type 1 (with 1 entrance), part of the Stelling van Amsterdam (Defense Line of Amsterdam, a Unesco World Heritage Site), specifically called the Positie bij Spaardam (the Postion of Spaarndam). The bunker was designed as a shelter against shelling and bombing, if the dike and the trench (along which the bunker is located) offered insufficient coverage. The spot now lies in an abandoned Defense ammunition depot and is hardly accessible due to the many bushes.
It is one of the many bunkers that were built during World War I between Fort benoorden Spaarndam and Fort bezuiden Spaarndam. There were several types, including type 1 (1 entrance) and type 2 (double entrance).
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