Of course, there are a lot more links to the places/businesses mentioned.
I only quote those that gave me a permission to do so.
Thank you very much to everyone who contributed.
I am sure you will find all further information via your search engine.
If you discover any broken links please let me know...
Dunnottar Castlehttp://www.dunnottarcastle.co.uk
Official website of Dunnottar Castle
Dunvegan Castle
Official website of Dunvegan Castle, Isle of Skye
Edinburgh Castle
https://www.edinburghcastle.gov.uk/
Official website of Edinburgh Castle
Eilean Donan Castle
https://www.visitscotland.com/info/see-do/eilean-donan-castle-visitor-centre-p248371
Information on Eilean Donan Castle, Highlands
Inverewe Gardens
https://www.nts.org.uk/Visit/Inverewe/
Find out about Inverewe Gardens and Estate, Highlands
Royal Botanic Garden Edinburgh
Official website of the Royal Botanic Garden Edinburgh
Urquhart Castle
https://www.visitscotland.com/info/see-do/urquhart-castle-p245811
Urquhart Castle - one of the most popular spots on Loch Ness
St. Andrews Castle
https://www.historicenvironment.scot/visit-a-place/places/st-andrews-castle/
Information on St. Andrews Castle, Fife, provided by Historic Environment Scotland