I was gonna post those TF2 shots, but I couldn't find them anymore, so that's why I didn't. It's pretty much like CJ and Peris said, I copied that part on purpose. I've always thought that this TF2 map looked incredibly cool (despite its age), so one day I just felt like recreating as much as I could from the screenshots. After I had done that, I just expanded the map like I felt.
That's all. It's pretty much like how DaveJ started de_dust.
I'll tweak the lighting. The TS version is supposed to have roof access, but atm it's having some r_speeds issues on said roofs, so a lot of tweaking has to be done.