This is probably the illustration with more buildings that I've ever done. It took a while and it wasn't easy, but finally it's done. I hope you enjoy it. I share the process below.
Firstly, I did the line, it took a while but it was worth because it allowed me to take the process of painting under control. After that, I did some value studies, trying to find the best illumination for the story that I wanted to explain. Once I have my value election done, I did some fast color keys, looking for a good palette. Then, I started the clean-up process, and finally, I applied some textures and effects.
These are the three value studies for this illustration. As you can see, everyone explains something completely different, depending on where the light comes from.