Eilean Donan  Castle  at Kyle of Lochalsh on the west coast of Scotland .   A  13th Century  Castle initially built to defend against the Viking invaders. This Iconic has been used in numerous movies such as Highlander , Elizabeth and 007 world is not enough to name a few. 

Duffus Castle .. A medieval stronghold of the Moray family built in the 1100s 

Dunnottar Castle on the north east coast , home of Earls Marischal once one of the most powerful families in Scotland. 

Dunrobin Castle . Still inhabited today,  dating back to the 1300 century. Home to the Earls and Dukes of Sutherland.