The Varbola Stronghold was the largest circular rampart fortress and trading centre in Estonia in the 10th-12th centuries. The first record of Varbola is written by Henry of Livonia, who mentions the Castrum Warbole being besieged in 1211 for several days by Mstislav the Bold of Novgorod. The conflict was resolved with a payment of seven hundred Marks.
During the Livonian crusade Livonian Brothers of the Sword invaded the territory and the people from Varbola asked for the terms of peace. The terms offered by Livonian Brothers of the Sword were accepted by Varbolians, but later the people of Varbola became the subjects of the King of Denmark. On the basis of the Danish Census Book the estate surrounding the Varbola trading center remained a possession of the Lode family, nobility of Estonian origin at the time. The Varbola stronghold lost its importance only in the second quarter of the 14th century, after having played in important part in the anti-Christian and anti-German St. George's Night Uprising of 1343.
In the 16-17th centuries the stronghold was used as a cemetery. The first known fort plan dates from 1786 and was drawn by Ludwig August von Mellin. Archaeological excavations at the site have been undertaken in 1938-41, 1953 and 1974. Among the archaeological finds were dice made of bone.
Parts of the ruins of the 580 metre long and 8-10 metre high limestone wall of the fortress stand still this day. The long gateways with multiple gates were built to defend the entrances. In these sections higher defensive towers were erected. There was a 13 metre deep well in the middle of the fortress and the territory held about 90 structures with furnaces for accommodation built with limestone floors and foundations.
Reference: Wikipedia
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.