"Underneath the soil"
On your 6x6, make us something underground, maybe like a city sewage. So long as it is underground. Also, we would like to see the top of the ground, so grass or plants, whatever. Also, NO overhang! Not even a little on this one! Go crazy.
I very much like the way you did the rocks on the bottom. I also like the cleanliness of it. The tower of Barad Dur is a bit off scale with the trees, but I won't judge that. This was a tough choice, but you get my vote!