Kaliningrad used to be known as Koenigsberg, and was the seat of the traditional rulers of Prussia. The city was eventually overshadowed by Berlin, who unified with Koenigsberg in the mid-17th century to form Brandenburg-Prussia. From then on, Prussia would be ruled from the capital of Brandenburg, Berlin. However, Koenigsberg (Kaliningrad) remained the regional capital of Eastern Prussia. Many of the ruling elite of Prussia, especially prior to the Napoleonic Wars, owned land around Koenigsberg.

Following World War Two, Russia completely rearranged the territory of many Eastern European countries, including Poland, Ukraine, Lithuania, and East Germany. Traditionally Germanic areas were given over to Poland, and the Germans were expelled from the region. As per the Potsdam Conference, Prussia was officially dissolved as a political entity, and most of the lands of east Prussia were doled out to Poland and Lithuania. However, the city itself was kept by the Russians, who saw it as the capital of the traditional political enemies, the Prussians. The city became a major base for Russian forces, a testing ground for all sorts of weapons, and a generally not nice place. It served as a piece of propaganda, to demonstrate what happened to Russia's enemies. After the dissolution of the USSR, Kaliningrad was kept because of its strategic location on the Baltic Sea. The region still houses a large Russian force, and would be a great base of operations in the event of a Russian attack against the Baltic States or Poland. The Base still has major geostrategic importance.

As result of Potsdam Conference of the Heads of Government of the USSR, USA and UK; July-August 1945. This decision was a part of the rather more complex agreement about future of defeated Nazi Germany and its allies.