The Sandomierz Royal Castle was built on a slope of Vistula River by Casimir III the Great and extended in the 16th century. The original building was blown up in 1656, leaving only the west wing standing. It was later transformed into a Renaissance styled residence with the west wing preserved as a museum.
The 14th-century castle was built on the site of the existing stronghold in the 10th century. Between 1146-1166 it was the seat of Prince Henry of Sandomierz, son of Bolesław III Wrymouth. The Gothic castle was built by Casimir the Great. The remnants of the Gothic structure are visible in the foundations of the octagonal tower of the south corner, which is the oldest part of the monument. The existing tower was built during the reign of Casimir IV Jagiellon in the 15th century as an integral part of the so-called Great House, the seat of the prince.
During the reign of Sigismund I the Old and Sigismund II Augustus, the castle was enlarged. The Sigismund the Old's cornerstone preserved above the entrance on the east side of the array. It bears the date 1520 and a cartouche with Sigismund's eagle. The construction was supervised by the Royal architect Benedyct Sandomierski, who erected two-storey arcaded cloisters around a closed courtyard.
During the Deluge the castle was blown up by the retreating Swedish troops of general Sincler. About fifty Poles, who entered the abandoned castle, were killed. The survived western wing of the castle was later rebuilt during the reign of king John III Sobieski between 1680-1688.
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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.