This is perhaps one of the most disturbing places I have ever been, simply because of the eerie stillness of the surrounding woods. Dachau was the longest running concentration camp, it opened the day before Hilter got into power, and closed days before he died, and it is a haunting but unmissable experience. Do not go expecting a laugh and a good time, but instead prepare yourself for something you will never forget.
Auschwitz is a very similar feeling. No ones wants to talk in more than a whisper, and the museum itself is rather cold and still. Large displays behind glass contain thousands of toothbrushes, shoes, dolls, and even hair. There is so much to learn in a place like this, and the feeling is never forgotten.