Well, i don't understand the random darker tiles on the foreground, what is the point?
The Brick tiles won't vertically tile, so you decided to fix that by adding a tile that is even more obvious when tiled?
The vines (or whatever they are) is only on the bottom, realistically would be sporadic and all over the place, not just the bottom.
And for added realism, something holding the "floating bricks" up would be nice.
And lastly the background looks horridly tiled and unrealistic. It could use some work.