alt Hacker NewsI mean no, it's not.
Castle Sween was built in the 11th century (and might still not be the oldest).
Dalhousie Castle was built in 1247 and the oldest bit of the surviving castle is from the 15th century. Most of it is from the 17th century. The roof is post-2004.
The actual lesson is, if you want to leave a legacy, hope someone rebuilds it when it falls apart after you're gone.
There's no need to correct. They had a lovely holiday at what they thought was the oldest castle in Scotland. Leave them to it instead of jumping in with 'actually, I've identified at least three castles older, and while we can't be certain which is the oldest fort in Scotland, we can be confident that it wasn't the one you thought you had a nice time at'