It was constructed under the German rule in 1910 by Franz Schwechten for William II, German Emperor, with significant input from William himself. Since its completion, the building has housed government offices of Germany (to 1918 and during the Second World War) and Poland (1918–1939, 1945–present).After the Greater Poland Uprising (1918–1919), the castle became the property of the Second Polish Republic and was used by the legislator and as the home of the Polish president. After the incorporation of Greater Poland into Nazi Germany in 1939, the authorities decided to transform the castle into Adolf Hitler's residence. Most of the rooms were changed into the style of the Third Reich. Under the castle, a bunker for 375 people was constructed. The rebuilding was stopped in 1943 due to the Germans' negativity from setbacks on the Eastern Front.During fighting in 1945, the castle was a temporary camp for German POWs, and was later used as a barracks by the Polish People's Army. During this period, the communist government considered the demolition of the castle as a symbol of the German occupation and bourgeois style. Due to a lack of funds, only some of the German symbols were removed and the upper part of damaged tower was demolished.