The Nus castle stands above the same name village on a rocky projection, which dominates the entrance to the valley of Saint-Barthélemy. According to available documentation, the building can be traced at least as far back as the end of the 13th century, although the quadrangular turret, which collapsed at the start of the 20th century, and which stood in the eastern sector of the castle, can be compared to the towers erected in the valley during the 11th and 12th centuries. The final layout of the castle, which was modified on several occasions during the 14th and 15the centuries, was the product of a radical reconstruction campaign which took place around 1595, the date inscribed on the architrave at the entrance to the courtyard.
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.