The only reason France in particular was able to preserve alot of its architecture was because even the Nazi's couldn't bring themselves to destroy the beautiful edifices that are so prevalent in France. In fact, France was the place the Nazis used to unwind after a long day of baking jews and massacring entire villages of eastern Europeans. Perhaps one of the few good decisions Hitler made was deciding not to level France to the ground because its beauty was undeniable.
Furthermore, France's decision to surrender early also helped avoid alot of the wanton destruction that many of the European countries that went toe to toe with the Nazi's suffered.
