This morning President Obama, Elie Wiesel, Angela Merkel, and others are touring Buchenwald, a Nazi concentration camp outside of Weimar, Germany. Elie Wiesel was a teenager when he was captured by the Nazis and put into a concentration camp. His story and experiences were told in his book, Night. Buchenwald was just one camp, but the horror of the Nazis was repeated over and over again all over Europe until the Allies stopped the madness.
If you are interested in additional reading material about Elie Wiesel, and the Holocaust, I'd suggest the following list of books (this is a small list):
Night, by Elie Wiesel
The Theory and Practice of Hell, by Eugen Kogon
The Upstairs Room, by Johanna Reiss
The Diary of Anne Frank
Anne Frank Remembered, by Miep Gies
Survival in Auschwitz, by Primo Levi
From the Ashes of Sobibor, by Thomas Blatt