Update: Fixed the lines in the roof and also adjusted the overall width of the building, which was about 8 meters smaller than the actual building.

@Darf, thank you for having me look into this again, I would have just left it had you not. I completely re-unwrapped the roof in a different way and got it to load without those lines, so you were right, they were in the UV somewhere, that still baffles me because I cannot figure out why those were appearing, but oh well. I am going to make some other minor fixes while I'm in the model and I will upload an update. Thanks again! This is the second time a really experienced asset creator has helped me make improvements to an asset and I love the community and the feedback in Cities!

I am going to play around with this some more, see if I can find anything in the UV

The white lines are probably, because your UV map ends near a white line. Mapping it 5 pixels away on the blue surface will probably resolve the issue.

FYI, I have no idea why the thick white lines are in the roof, there is nothing like it in my model or texture and I can only think that it is the way the game generates the dome architecture for some reason. The alternative, which I have played around with, is to remove the smooth shading on the dome and leave it unaltered, which created a very polygonal, disco ball-like appearance. I feel that the lines and the smooth reflective appearance of the roof are a better solution. Hopefully that isn't too big of a deterrent for folks that want this building, enjoy!