According a tradition there has been a defensive complex here since pre-Roman times. The Rocca fortress was built in the late 12th and early 13th centuries. The last military operation took place in 1510 and after that Rocca was moved as hospital and private use.
The fortress was involved in his latest war episode in 1510 . Gradually Persa's strategic importance, the structure was used as a variety of uses also becoming hospital during the continuous plagues of the sixteenth century. Decommissioning in 1650 , Venice even tried to sell it to private.
The massive construction has a polygonal plant of nine unequal sides. There are no open slits or windows: only one door gives an access to the upper defensive system of the city.
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.