Plainburg Castle - the family seat of the Counts of Plain and a symbol of Großgmain - is one of Austria's oldest castle ruins and offers a magnificent view over Großgmain and the surrounding mountains. All that remains of the original structure are the outside walls, with a thickness of 1.4m and standing to a height of over 5m. A short climb rewards the visitor with the opportunity to stop and rest awhile at the viewing platform overlooking Großgmain. Before it became the seat of the Counts of Plain, the mountain was a Celtic burial ground during the late Bronze Age around 1200 BC. Some time later, in about 1100 AD, Count Werigand of Plain built Plainburg Castle.
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.