The Crusader structures called the Knights' Halls or the Citadel of Acre originally served as the Knights Hospitaller Compound. They extend over an area of c. 8,300 square meters. Archeological remains from the Hellenistic Period (300-63 BC), from the Early Arab Period (638-1099 CE), to a large extent from the Crusader Period (1291-1104 CE) and primarily from the 13th century, were uncovered in the compound area.
It was in the 13th century that Acre was the capital of the Crusader Kingdom of Jerusalem. The destruction of the Crusader structures during the Mamluk Period (1291-1517) left its mark on the compound.
During the Late Ottoman Period (1750-1918 CE), the citadel was built as part of the city's defensive formation on the ruins of the Crusader fortress and during the British Mandate (1918-1948), activists of Jewish Zionist resistance movements were held prisoner there and it served as the main prison in the North of Israel. The archaeological excavation of the Crusader remains and the exposure of a multi-period complex depict Acre's two golden ages – the thirteenth century and the eighteenth & nineteenth centuries.
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.