Very attractive castle in the Scotish highlands – it lies at the point where three Scottish Lochs Meet. It is that much of a well known, loved, castle that it has its own website – http://www.eileandonancastle.com/
Sadly, from a purely historical point of view, this is not a castle that has really seen service (compared to the ones further south for example) and is closer to the stately homes of rich nobles (Castle Drogo for instance)
Still Eilean Donan is a stunning building and very imposing. This photograph (from Flickr) is an excellent example.