Maasi medieval fort-castle was built with the forced labour of islanders. That's how the ruling Liivi order punished indigenous inhabitants for the uprising, which had destroyed orders previous stronghold. Seaside fort-castle was undefeated until destroyed by Danes. The fortress was blown up in 1576 by the Danes in an attempt to forestall the Swedish invasion and nothing was done for the next 300 years. 8m walls that survived the destruction have become a landmark.
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.