Hässelby Castle (Hässelby slott) was built first in the 1640s by the riksråd Karl Bonde, who owned it until his death 1652. The original architect was Simon de la Vallée and the castle was finished about the 1660s by his son Jean de la Vallée, when Karl's son Gustaf Bonde owned it. The Bonde noble family owned the castle until 1931, when Stockholms stad bought it until 2010. Since 2010 SIVAB own the castle. Today Hässelby is opened for weddings, parties and conferences.
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.