Cecilienhof Palace was built from 1914 to 1917. Emperor Wilhelm II ordered the establishment of a fund for constructing this new palace at Potsdam for his oldest son, Crown Prince Wilhelm (William) and his wife, Duchess Cecilie of Mecklenburg-Schwerin on 19 December 1912. Cecilienhof was the last palace built by the House of Hohenzollern that ruled the Kingdom of Prussia and the German Empire until the end of World War I. It is famous for having been the location of the Potsdam Conference in 1945, in which the leaders of the Soviet Union, the United Kingdom and the United States took important decisions affecting the shape of post World War II Europe and Asia. Cecilienhof has been part of the Palaces and Parks of Potsdam and Berlin UNESCO World Heritage Site since 1990.
References:Rosenborg Palace was built in the period 1606-34 as Christian IV’s summerhouse just outside the ramparts of Copenhagen. Christian IV was very fond of the palace and often stayed at the castle when he resided in Copenhagen, and it was here that he died in 1648. After his death, the palace passed to his son King Frederik III, who together with his queen, Sophie Amalie, carried out several types of modernisation.
The last king who used the place as a residence was Frederik IV, and around 1720, Rosenborg was abandoned in favor of Frederiksborg Palace.Through the 1700s, considerable art treasures were collected at Rosenborg Castle, among other things items from the estates of deceased royalty and from Christiansborg after the fire there in 1794.
Soon the idea of a museum arose, and that was realised in 1833, which is The Royal Danish Collection’s official year of establishment.