More than 80 Holocaust survivors returned to Auschwitz on Wednesday, the 71st anniversary of the Nazi concentration camp's liberation.
Situated in southern Poland, the site now serves as a memorial to the millions of people murdered as part of Adolf Hitler's drive to exterminate the Jewish race and other minorities.
"Auschwitz is and remains a great warning of what can happen when international law is broken and the international community does not react," Polish President Andrzej Duda said in a speech to mark the 71st anniversary of the liberation of the camp.
He described the losses suffered by both Jewish and Polish people in World War II concentration camps as "unimaginable."
On Wednesday morning, camp survivors laid flowers against the so-called wall of death at Auschwitz, where inmates were lined up and shot en masse.
"We have to fight for peace and friendship so that this can never repeat. That is my goal and that is why I come back here every year," said Eugeniusz Dabrowski, a former prisoner at Auschwitz.
Asher Aud, an 86-year-old survivor from Israel, stressed the importance of remembrance. "Carry the memory on, pass it on to further generations," he said, adding that the lessons learned from history should "resound like an echo through centuries."
Events took place across the world to commemorate the anniversary of January 27, 1945, when Russian troops freed around 7,500 survivors at Auschwitz-Birkenau, Nazi Germany's biggest concentration camp.
The German parliament fell quiet at midday on Wednesday for an hour of reflection, focusing this year on the issue of forced labour.
Federica Mogherini, the European Union's foreign policy chief, said that the atrocities of World War II had left an "indelible scar" on the continent.
She argued that the battle against anti-Semitism was ongoing today and also urged Europeans to confront "fear of diversity, the temptation to look for scapegoats in difficult times."
At the United States Holocaust Memorial Museum in Washington, Holocaust victims were remembered, survivors in attendance lit candles to symbolize life and remembrance and speakers spoke of the horrors of the Holocaust and the importance of eliminating discrimination and anti-Semitism.
"Here we are saying in our tongue, he who saves one life is as though he saves the world," said Johanna Neumann, Holocaust survivor.
At the United Nations in New York, Secretary General Ban Ki-moon said teaching new generations about the horrors of the Holocaust is key to fighting xenophobia and preventing new genocides.
"I urge everyone to denounce political and religious ideologies that set people against people,” Ban said.