I have reference materials about the single most important architectural event in Minneapolis: the destruction of the Gateway. I can also provide you with many pictures of long lost buildings from the 1860s onward that show what used to be around at the time some previous ice palaces were built. I even have a menu from the West Hotel! lileks.com has some really good pages examining current and past MPLS architecture, too.

K. [about architecture as a field, the other advice you've gotten is good, I think]