Sachesenhausen Concentration Camp-
It may be a little insensitive to rate a former concentration camp as a highlight, but the historical tour I went on was hugely interesting. Located about a 50 minute train ride outside of Berlin in the town of Oranienburg, the concentration camp is huge and has more exhibits than there is time for. Although most of the buildings are reconstructions you can still get a good sense of what life in this work camp would have been like - especially as we visited on a freezing, overcast and windy day. The most chilling part was probably the intact dungeon-like rooms that had been used for storing corpses after people died from exhaustion, starvation, or beatings.