The original castle on the site of current Château de Combourg was built around 1025 by Archbishop Guinguené, who gave it to his illegitimate brother Riwallon. Major alterations were made between the 15th and 19th centuries. The castle consists of four large, powerful buildings of dressed granite, with crenellations and machicolations, enclosing a rectangular courtyard. In each corner of this massive fortress is a round tower, also with crenellations and machicolations, with conical roofs. In 1761, the Chateaubriand family acquired the property and it was the childhood home of François-René de Chateaubriand (1768–1848).
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.