alittle more colour in the grass, tree, and stones. not so smudgy, use the pen tool to thicken up the edges. it'll look good when it's finished, i've got a feeling about it.
To me, this looks like Stonehenge. As I recall that's a fairly large structure. The foreground tree makes the stones look tiny by comparison. I think if you lose the big tree, and put some small boulders and a few small shrubs, the scale will look more like what it should.
drawn in 1 hour 17 min