These two items for visiting Berlin seem somewhat archaic and stereotypical. The Sachsenhausen concentration camp is north of the city on the S-Bahn going to Oranienburg. But it really isn't on the same level as Auschwitz. Or even Dachau, for that matter. It was basically used for forced labor to work in the heavy industry that existed there up until the end of the war. As for the Berlin Wall, well, maybe there is a novelty about seeing what is left of it. The section up by Bernaustr. in Prenzlauerberg is one option. The other is near Warschauerstr. U-Bahnhof by the river. Quite frankly, there is too much to do in Berlin. And not enough for just two days. You might be better off just doing things ad hoc as you go about the city. No matter where you are at, there will be something of interest.