In the 19th century a system of fortifications was built around Königsberg (today’s Kaliningrad), the capital of East Prussia, with the aim of making the city impenetrable. This is how the “fortress city” came into being. However, the surrounding net of forts, bastions and barracks did not manage to defend the city during the Second World War. Faced by  new military technology, the 19th-century fortifications proved to be of little use. After the Second World War, the part of East Prussia with the capital fell in the hands of Stalin. After considering several different options, including the incorporation of the territory into Polish People’s Republic or Soviet Lithuania, the leadership of the Soviet Union decided to separate the fragment of East Prussia with Kaliningrad and turn it into a closed military zone. This is how the Kaliningrad Oblast was created, becoming the strategic westernmost bridgehead of the USSR.