There are an abundance of castles in the local area, including:
Balmoral Castle
Picture awaited- it is possible to visit as a tourist (there is a tearoom/gift shop etc.) when the Queen is not in residence.
Crathes Castle
Crathes Castle is on the eastern outskirts of Banchory. Noteable for its large walled garden, very nice/modern/family friendly tearoom as well as some great (young family length) parkland walks.
Drum (NTS site)
Drum Castle is 6 miles east of Crathes Castle, heading towards Aberdeen. We like this one for its old wood walk, family chapel and sympathetic combination of very old (unrestored) tower and more modern (everythings relative) house, with a library curiously sandwiched in the middle of the unrestored tower.
Cragievar
Picture awaited!
Castle Fraser
(not strictly in Deeside, but not far away.) Known for its impressive steam engine/tractor/classic car event in June.
Braemar
Corgarff
Kildrummy Castle (near Strathdon). On a fine day you might also like to enjoy a cream tea
on the lawn of nearby Kildrummy Castle Hotel (below).
Dunnottar Castle
Located just off the main A92, less than two miles south of Stonehaven.
www.dunnottarcastle.com, Tel. 01569 762173. Spectacular Coastal Setting
Knock Castle
The above is Knock Castle, which is walking distance from Cornellan Cottage. It is open to the public and the elements but makes a nice quiet destination for a picnic on a summers' day.