I'm not capable of imagining any fictional building without my head randomly picking from a handful of real building I've been to. And which one it picks will often be completely random and not the best suited to what kind of place it actually is. It's always either a specific one of the many apartments I lived in as a kid (but only the one), particularly my parents' bedroom in that apartment for some reason; the house of my best friend in late elementary school; or my old high school even if the fictional place isn't a school at all sometimes. That's it, that's all I ever see.