Mystras, the ‘wonder of the Morea’, developed down the hillside from the fortress built in 1249 by the prince of Achaia, William II of Villehardouin, at the top of a 620 m high hill overlooking Sparta.
The Principality of Achaea was one of the three vassal states of the Latin Empire which replaced the Byzantine Empire after the capture of Constantinople during the Fourth Crusade. It became a vassal of the Kingdom of Thessalonica, along with the Duchy of Athens, until Thessalonica was captured by Theodore, the despot of Epirus, in 1224. After this, Achaea became for a while the dominant power in Greece.
The Franks surrendered the castle to the Byzantines in 1262, it was the centre of Byzantine power in southern Greece, first as the base of the military governor and from 1348 as the seat of the Despotate of Morea. Captured by the Turks in 1460, it was occupied thereafter by them and the Venetians.
Today impressive ruins of Villehardouin's Castle still remain.
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.