I don't know of another movie, ever, that has so perfectly captured the banality and flat-out bizarreness of evil.
I really can't recommend it enough but it's a tough watch. Horror is lurking in the background throughout.
PS: If you have the chance to visit Auschwitz, you should. Or any concentration camp now open to the public. The best way for us to never revisit this monster-level bullshit on humanity again is to have to go confront it in all its ugliness, face to face. (Like when you walk around Berlin and you see all the Stolpersteine -- "never forget" -- memorials embedded in the city's sidewalks). What Steven Spielberg is doing with The Shoah Foundation will tower over any of his accomplishments in cinema. Preserve the truth. Witness.