The palace was originally a fortress, begun by Fulvo do Castello in 1215 for the Republic if Geneo. This is the only section of the fortress still standing - the Serravalle Tower.
During the French Revolution the palace was turned into a military hospital and was rand sacked. Prince Albert I (1894) commissioned the construction of the Tour de l'Horlofe (clock tower) and finally Prince Rainer III had the southern wing completely rebuilt.