I love this piece you've got. The lights are there so it the mood and the colors. I agree with the comment above. As the tree grows, it displaces anything above it, so you might see a lot of huge cracks and small debris everywhere. Try connecting the ground to the pillars too. In an area like this, will have a feel of slightly damped feeling, meaning there would be small vegetation climbing the walls and small algae...
When doing color bleeding, use Dodge tool instead of lens flare, lens flare usually looks fake when used wrongly.
Aside from those small things... superb work pare!
I really love this piece of work! My only concern is for the tree at the center to grow, maybe more destruction on the roof or more openings will be good. Coz they need sun lights. Plus, more lights at the center will draw more attention. Other then that, I think its sweet~!