Holocaust victims remembered at Auschwitz, in Warsaw and beyond

A Serbian military honor guard stand to attention during commemorations for victims of the Holocaust at a monument erected in the former World War II Nazi concentration camp of Sajmiste in Belgrade, Serbia, Sunday, Jan. 27, 2013. The ceremony coincided with International Holocaust Remembrance Day, which marks the liberation of the Auschwitz Nazi concentration camp on Jan. 27, 1945. (AP Photo/Darko Vojinovic) (The Associated Press)

Serbian military honor guards participate in commemorations for victims of the Holocaust at the former World War II Nazi concentration camp of Sajmiste in Belgrade, Serbia, Sunday, Jan. 27, 2013. The ceremony coincided with International Holocaust Remembrance Day, which marks the liberation of the Auschwitz Nazi concentration camp on Jan. 27, 1945. (AP Photo/Darko Vojinovic) (The Associated Press)

Memorial candles are lit in front of a photo taken during WWII showing refugees fleeing from the Nazis at a ceremony marking International Holocaust Remembrance Day in Russia’s first Jewish Museum in Moscow, Russia, Sunday, Jan. 27, 2013. (AP Photo/Alexander Zemlianichenko Jr) (The Associated Press)

Holocaust survivors, politicians, religious leaders and others are marking International Holocaust Remembrance Day with solemn prayers and the now oft-repeated warnings to never let such horrors happen again.

Events Sunday took place at sites including Auschwitz-Birkenau, the former death camp where Hitler's Germany killed at least 1.1 million people, mostly Jews, in southern Poland. Sunday is the 68th anniversary of the liberation of the camp by Soviet troops in 1945.

In Warsaw, prayers were also held at a monument to the fighters of the Warsaw Ghetto Uprising of 1943.

And in Rome, Pope Benedict XVI warned that "the memory of this immense tragedy, which above all struck so harshly the Jewish people, must represent for everyone a constant warning so that the horrors of the past are not repeated."