I read another article about this somewhere recently (PBJ or AZBEX maybe?). Anyway, I thought it must be near us here in Casa Grande - but they aren't saying officially. How did you come up with that and do you have exact location?
Is it near Picacho Peak? I cant tell exactly from the pictures of the site....
EDIT: I see the reference to south of CG on one of the pages on that website - but still doesn't say exactly where it is - and the site is pretty outdated - but again I did see another article on it very recently so it is still a project.
Found the link to the recent article:
http://www.eastvalleytribune.com/get_out/article_32f43d50-6f55-11e4-be23-dfcfd681799a.html
More edit: Should have done my own research - its going to be on the Tohono Odham Reservation according to this article:
http://kjzz.org/content/69335/project-hopes-build-massive-scale-earth-model-arizona
So that would be basically south of I 8 and west of Arizona City.
2020 is a long ways away though - but I do hope this comes to fruition - might help stimulate some hospitality related development along I 8....