The Barrow Downs ... just by its name ... draws interest from Tolkien book people who have read about the Barrow Downs. It wasn't mentioned or shown in the movies. In fact, the closest thing to come to it in the movies was the burial mounds of Rohan.
A good discussion on the finer aspects of Tolkien's written works can usually be had here, and the stability of the site not wanting to make changes to the latest gimmick or try to expand its scope to draw people in makes it what this Tolkien book geek loves!
