Wow! This is amazing work! It resembles a bit the venus project structure of city

Nice rendering!!!

How did you make the background? Is it rendered?

I agree. Excellent job on rendering. The lighting soothes the ambiance you have created. I feel like living in that kind of city. I just want to escape to that city and experience how it feels. The background really defines the quality of your work. I may also say that you are really creative artist with your choice of viewpoint which emphasizes the beauty of your cityscape.