Since the incorporation Kesselstadts after Hanau 1907 the castle is located in the town of Hanau. The city took over 1919/20 in its custody and placed it on behalf of the heirs for sale; However, there was no buyer.
In 1943 the furniture was largely outsourced to Schloss Pheasantry (also called Schloss Adolfseck) near Fulda to protect it from bomb hits; In hindsight, this measure proved to be wrong, as Philippsruhe remained intact, while attacks on Fulda affected the outsourced inventory.
Since the end of the Second World War, the castle, which acquired by the city of Hanau in 1950, served as a commercial and living space and finally as a town hall, as the entire city centre including the historic town hall on the market square, due to the heavy air raid of 19 March 1945 had been completely destroyed. In 1964, the city council could move to the rebuilt town hall in the city centre, and 1967 opened the first rooms of the Historical Museum Hanau in Philippsruhe.
The castle also houses a separate paper theatre museum in some rooms next to the Historical Museum Hanau.