New Slains Castle, to distinguish it from nearby Old Slains Castle, was originally a 16th-century tower house, built by the 9th Earl of Erroll. The wings around the courtyard were extended in 1664 by addition of a gallery or corridor, and in 1707 the entrance front was renewed.
In the 1830s the 18th Earl commissioned the Aberdeen architect John Smith to remodel the castle. This resulted in a virtual rebuilding of Slains in a Scots Baronial style, including granite facings, in 1836–1837. Gardens were laid out in the late 1890s.
At first inspection the ruin appears to be a blend of several different architectural styles and periods, due to diverse masonry including older mortared granite, mortared medieval red brick, mortared sandstone and newer well faced granite. In fact most of the architecture seems to derive from a rather cohesive interval 1597 to 1664, which construction is the most expansive and includes the mortared rough granite and medieval brick. The 1836 work adds smoother granite facing that contrasts with the older construction style.
The defensive works of the castle include use of the North Sea cliffs; an abyss to the west that functions as a deep impassable moat; and a ruined rampart that would have been the main entrance on the south. The ruins include reasonably well preserved elements of three- and four-storey structural elements and a basement course over some of the range, especially at the eastern side. There are well-preserved basement kitchen works with numerous firepits and masonry indented storage spaces. The internal doorways are primarily of well-preserved wooden lintel construction, with numerous examples of mortared sandstone and medieval brickwork archways. The interior of the ground level is a maze of passageways and smaller rooms, reflecting a high state of occupancy in 17th-century times.
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.