The Castle of the Masovian Dukes in Czersk was built on the turning point of the fourteenth and fifteenth century by Prince Janusz I. When the Masovian land became part of the Kingdom of Poland - which was under the rule of Queen Bona Sforza. Primarily, the castle had three towers, one of them - being four-sided, was used as the main gate house.
During the war with the Swedes, in 1656, the castle became partly ruined. The retreating land army, close to Warta, under Stefan Czarniecki"s commandhad captured the stronghold and had devastated it. The castle went through a reconstruction between 1762-1766, when Marsza³ek Franciszek Bieliñski had commanded the reconstruction of the stronghold. However, due to the Prussian Partition, the Prussian leader had ordered for the demolition of the castle"s defense walls, reducing the stronghold"s military importance. From that time, nobody had every again took on the reconstruction of the castle. From the once mighty stronghold, all of the towers; a brick bridge from the eighteenth century; and the north and east wing of the castle had all survived.
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.