The so-called Piasts' Castle in Gliwice dates back to the mid-14th century. It consists of a tower from 1322, which was originally part of the city walls, and an adjoining building which was probably an armory. Modifications were carried out in the 15th century, between 1558-61 it became the residence of Friedrich von Zettritz. Later it was an armory, a jail, a magazine and since 1945 a museum. Between 1956-59 it was thoroughly rebuilt and partially reconstructed. Since that time it is claimed to be a Piast castle, although no sourced evidence backs this claim. Since 1959 the castle has been part of the Gliwice Museum.
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.