King Duncan's Ghost by the River Ness

The history is weak. Wikipedia notes that Inverness Castle is said to have been built by Malcolm III after he razed the castle where Macbeth, according to much later tradition, had murdered Malcolm's father Duncan I, and that earlier castle stood about a kilometre north east. The historical Duncan I was killed in 1040 in battle, probably near Elgin, and the murder in a castle belongs to Shakespeare's play. The Duncan ghost is therefore a literary story in a real place. Treat it as folklore only.