SilverWook said:
I thought it grew out of the concept of a capital for the Empire, that existed in Lucas' early script ideas. (Which Timothy Zahn expanded on and gave it a proper name?) There is pre-production art dating back to the OT.
That's it. I'm not really an early script guy, but I think it was what Alderaan was originally going to look like. Seems like the Empire taking up residence came later when Alderaan had a separate identity. Others will have to weigh in here.