The Castle can be visited
Blair Castle

In Blair Atholl, Scotland, stands Blair Castle. Its history dates back to the 13th century and it is closely associated with the Murray family, whose head is the Duke of Atholl. A unique feature is the stationing of the Atholl Highlanders, Europe's only legal private army, which today performs purely ceremonial duties.
History+
The origins of Blair Castle trace back to 1269 when John Comyn began its construction. This led to complaints from the then Crusader Earl David of Atholl, who nevertheless managed to reclaim the estate for the Strathbogie dynasty. The Earldom of Atholl, one of the oldest in Scotland, changed hands multiple times. In 1457, it was granted to John Stewart, the progenitor of the current House of Atholl. Later, the title passed to John Murray.
Source: Wikipedia · Licence: CC BY-SA 4.0 · Image: https://de.wikipedia.org/wiki/Datei:Blair_castle_-_facade.jpg
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: 56.7734, -3.8576