On the 27th January 1945, the Auschwitz-Berkenau death camp was liberated by the Red Army. That day now stands as Holocaust Memorial Day. Anyone who has not visited the museum and the former camps that are now preserved just outside Krakow, I'd recommend a visit. It's not pleasant, but it's a place on Earth like no other.
Auschwitz-Berkenau is one of the eeriest places I've ever visited. Remember it was not only Jews who died there but also Romanies, Poles & Russians.
I've not been, but i did go to the 'killing fields' in Cambodia. A horrible experience, but hopefully if people go and see these sorts of places, it's less likely to happen again.
This is one place i really want to visit at some point when my little ones are older and can understand ill take them i think all future generations should be aware of what happened during that terrible time