Holocaust survivors and world leaders are marking the 80th anniversary of the camp's liberation at a memorial ceremony in Poland. We hear from one of the dwindling number of Auschwitz survivors, and speak to two distinguished historians about the warnings that the Holocaust still sounds.

(Photo: A general view of the area of the former Auschwitz camp. Credit: Jarek Praszkiewicz/EPA-EFE/REX/Shutterstock)