Hi Mario, I like where this one is going, it has a very clean and fresh atmosphere and looks like what I wish a modern city could be.
You have broken up the scene quite well using the large greenhouse and the treeline, and the use of natural materials such as the wood for the main arch is also a nice touch, which synergises well with the abundance of plant life.
A few things I noticed were the windows in FG left, seems a little bright for being in that much shade, I find a good trick is to create a desaturation adjustment layer to turn on when you need to check values without being distracted by colour.
Also the flower garden in the FG - is a great touch, but using diffuse light reference is very difficult for this kind of harsh late afternoon sun direction where there are long dark shadows. I think you may be better off using reference with shadows for this.
Those two trees FG right, I like their placement and how you have used them to break up the flat mid ground area, but the textures themselves seem a little oddly warped.
Lastly, the repeating textures on the water tanks stood out a bit to me, you could just paint in a few minor details to create some instant variation.
Overall, nice work on this one, I look forward to seeing more of your work. 
