Monschau Castle is first recorded in 1217 as castrum in Munjoje by Archbishop Engelbert I of Cologne. It was expanded in the middle of the 14th century into a fortress for the counts of Jülich and equipped with mighty ring walls and wall walks. In 1543 troops of Emperor Charles V besieged the site with heavy guns, captured it and plundered it together with the town of Monschau.
In the early 19th century the French administration declared the castle to be state property and sold it to a private buyer who had the roofs removed in 1836 and 1837 in order to avoid building tax. As a result, the castle fell into ruins until, in the early 20th century, the government of the Rhine province secured and repaired it. After the First World War a youth hostel was opened in the west wing. So Monschau Castle survived as a 'youth castle' (Jugendburg).
Within sight of the castle, on the other side of town, is another fortification, the Haller. It is disputed as to whether it was an outpost of the castle, a detached watchtower or the remains of an older castle site.
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.