This is a very interesting little video showing off how the Game of Thrones locations are built up using Computer Graphics, substituting effectively for matte painting in traditional film.
In my extensive reviews of the show one thing I’ve noted is that the “foreground” CGI elements are a little thin. There aren’t much in the way of magical swirls, lightning bolts (LOL) etc. The backgrounds however are incredibly lush — and subtly so, bringing to life the rich and detailed world. This video shows the intricate relationship between the art of the location scout, the set dressers, overall planners, and the CGI team. Pretty impressive!
Also don’t miss this second video with more effects, this includes a lot of action shots (getting stabbed, etc).