Rothenthurn ('red tower') castle may have existed since the 11th century. It was an estate of the Counts of Ortenburg and their successors, the Counts of Celje. A castle is documented in 1478, when the area was held by the Meinhardiner House of Gorizia. The present-day Renaissance building with its chapel was erected from the early 16th onwards, it was acquired by Christoph Khevenhüller about 1525 and afterwards in the possession of several local nobles over the centuries. Today the owners run the castle as a lodging establishment.
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.