Ah here we go,
I must say this is maybe not the ideal way of doing city stuff, as I struggled with it myself and I would probably try to do it in a different way, im not going to describe every step, but just the ones that matters.
1: here you see a perspective layout with some cleaned up simple shapes in perspective,
but there should be a step before it with a very simple sketch I did to figure out the subject, how the composition should be and the perspective.
Basicly its better to do a freehand crappy sketch to figure out the idea and all, than make perspective lines to fit it.
2: Here I was thinking I could save time If I did a selection of each and every surface area, but in the end I think it just got in the way, it made figuring out the color scheme and lightning a real pain and adding atmosphere was impossible unless I wanted to add it as a last step.
Instead I should had freehand painted it as much as I could to figure out the lightning, color etc using a brush underneath the lines, like I did in a prevoiusly step I uploaded, with the interior (steps 2)
3. well here the issues started, it was really just a pain to visualise it, and working with so many layers just stopped any kind of flow I had in my painting, adding lightning and working with selections/locked layers is no fun.
4. adding more patterns to the simple building blocks I previously painted.
5. I think it might been here I abandoned most of the locked layers I made and started to add color adjustments to fix the lightning, it previously just felt too grey.
The rest of the steps is kinda more of the same, adding more details, atmosphere, doing some color adjustments and such.
At step 10 I did a quick laying of stuff I wanted to add the next day, like spaceships and such, I just had it as a reminder and also so I could see the placements of them,.
11. I made a copy of the image on top of all the layers and lighten up the distant background with a color dodge.