I'm surprised that no one has mentioned Neurenberg and the Nazi Documentation Center. After the war, the Allies ordered the construction of this permanent exhibition in order to provide a lasting reminder of the origin of the Nazis, how they seized power, and the outcome of their policies right down to photos of concentration camps, damage to German cities and the trial of the war criminals in Neurenberg. You can also tour the large rally grounds that are seen in many of the old film footages from that time. It was a moving experience, and as a history buff I learned many new things, as well as many questions I have had in my mind for years, answered. One of the most compelling displays were children's school notebooks (from about 2 - 5th grade) in which they wrote essays about how "bad" anyone who was not German was. The molding of these young minds was indeed very scary. A worthwhile visit.