Where to find textures and how to create my own

Hi guys!
I’m working on a small game set in 1956 of Hungary for a competition, and I need help with the enviroment. I roughly want something like this:

I already started modelling the houses and the basic shape of the whole thing, but I don’t know how I’m going to get it look the way I want it to.
What I did previously in a similar situation (when I had to create the UV map for the main character) is I looked up people from that time period and copied parts of their clothes in photoshop and somehow filled the UV map with them. That kinda worked that time, since I only wanted it to look presentable, nothing specia, but as you can see
It’s not the cleanest of UV maps out there. This won’t work on a scale of a building, and I want it to be recognizable as Budapest, or at least similar. I thought about drawing the textures myself but I have no idea how to even get started let alone create the whole texture of a building myself. I’d appriciate any kind of help. Thanks!