Just thinking on the spot here, but I wonder if an Immigration museum, focusing on, but not limited to the massive influx of German and Irish settlors would have a big enough draw? That would certainly tie into regional history and be interesting to lots of folks in the Midwest. Outside of the German and Irish core, you could easily tie in African-Americans, Scandinavians, Latin Americans, etc. Could actually serve as a type of cultural center as well, if done right. In fact, part of the description of the City Flag ("Standard") reads:"white shield edged in gold, symbolic of the character and courage of the varied nationalities of our ancestors,"Just a random idea...
Munice has a cultural center, Minnstrsita. Take a look at the website: