If it is undiluted wilderness that the makers of Harry Potter were after, they certainly found it at Rannoch Moor, also known as Great Moor of Rannoch. It is in many of the films, mainly in scenes that contain Hogwarts express. It is also the place that the Death eaters stop and board the train in Deathly Hallows part 1. A boggy, unforgiving landscape at certain times of the year.