I started the scene with a goal of making the front door of a police station, which evolved into a race track, which again changed into a roadside, and finally ended up looking like a back alley…so I guess I’m not the most dedicated artist out there

I am just starting to use blender and I hope to make stuff as well as you have done. You have asked for a critique so here is what I see. I really noticed the ladder. It is in the wall and you would not be able to climb it. You could make some brackets to attach it to the wall and it would look a lot better.
I really like the texture you used for the road. It is just too perfect. Maybe make some cracks. The same goes for the sidewalk.
Also the wall by the ladder is very flat. Andrew Price did a video on youtube on how to make realistic textures in Blender. Check it out. It is /watch?v=W07H7xeUnGE. I think it will really make that wall look really nice.