To be privately owned
Abergeldie Castle

Abergeldie Castle, a tower house in Scotland, was built around 1550. This four-story structure has been a protected monument since 1972.
History+
The construction of Abergeldie Castle took place around the year 1550, initiated by Sir Alexander Gordon of Midmar. An episode in its history was its occupation by Spanish troops under General Hugh Mackay during the first Jacobite rising in 1689. From 1848 to 1970, the castle was leased by the royal family, due to its proximity to Balmoral Castle. A local legend tells of the witch Katy Rankin, who was supposedly imprisoned here before being executed on a nearby hill.
Source: Wikipedia · Licence: CC BY-SA 4.0
This description draws on the facts documented in the linked Wikipedia article; Wikipedia content is licensed under CC BY-SA 4.0. Wording and editing: Mobile History.
Location: 57.0432, -3.1764