Although I greatly appreciate the artistry involved in beautifully styling sentences and recognize the importance of careful plotting and characterization, I'm curious about what may seem a more pedestrian aspect of writing: how do professional authors like Dan Simmons or, say, Donald Westlake go about the process of researching and organizing the "background" information that give texture to their novels?
For example, I notice in Dan Simmons's Joe Kurtz novels and in Flashback, he uses a large number of real-world locations and events around Buffalo and Denver. (Mr. Westlake did something similar in the Parker novels.) Specific instances might be the descriptions of the Harbor Inn or the Cherry Creek Mall.
Similarly, in his (more) science fiction novels, Mr. Simmons uses a large number of complex concepts from theoretical physics, mathematics, materials science, genetics, et cetera.
How do authors go about discovering such information and then organizing it and all the "world-building" details they must assemble to create a realistic-seeming setting for the interaction of these multi-faceted characters (all expressed through those wonderfully-styled sentences)?