Doune Castle, Doune
Excellent tour available. Where Monty Python and the Holy Grail and Outlander among others were filmed: https://www.historicenvironment.scot/visit-a-place/places/doune-castle/
Combining a visit to Doune Castle and nearby Deanston Distillery (see below) makes a great day out.
this ancient castle has recently been restored.
Stirling Castle, Stirling
a 30 minute drive from Appletree Cottage www.stirlingcastle.scot