Iburg is a ruined hill castle in Westphalia. It was build around the 8th century, dating back to the time of Charlemagne and his war with the Saxons. Today it is a popular day-trip destination and the tower, named after Charlemagne (Kaiser Karl Turm), can be climbed for beautiful views.
It is likely that the castle was originally erected by Saxons as a fortified stronghold but once conquered Charlemagne build a chapel within its confines to honour St.Peter, which he eventually gifted to the Arch-Diocese of Paderborn. From 1134 a monastery briefly used the castle before the Bishop of Paderborn fortified it to become a stronger military fortress in the late 12th century. The Iburg never saw much action, however, and slipped from importance until the 15th century, when Otto of Braunschweig destroyed it. The castle was not restored and the close-by city of Bad Driburg inherited the holdings.
First archeological surveys were undertaken on 1900 and gradually the ruins where freed and restored to serve as tourist attraction.
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.