OSWIECIM, Poland (AP) - Germany's president stood in silence Thursday before a gray concrete wall where Nazis executed Polish resistance members at Auschwitz, one gesture among many of his nation's remorse during somber commemorations marking the 66th anniversary of the liberation of the death camp. (Scroll down for photos) President Christian Wulff and the Polish president, Bronislaw Komorowski, laid wreaths at the wall and walked with former camp inmates beneath the entrance gate bearing the inscription "Arbeit Macht Frei" -- or "Work Sets You Free" -- a notorious slogan used by the Nazis in camps where they subjected their victims to slave labor, torture and murder.
The two leaders then traveled the short distance to Birkenau, the much vaster camp where Jews, Gypsies, and others were killed with factory-like efficiency in gas chambers.
"The name Auschwitz stands unlike anything else for the crimes perpetuated by Germans against millions of human beings," Wulff told a gathering of dignitaries and former camp inmates. "They fill us Germans with disgust and shame. They lay upon us a historical responsibility that is independent of individual guilt. We must never again allow such crimes to occur. And we must keep the memories alive."
Holocaust Remembrance Day
The ceremony at Auschwitz is one of several being held across the world on International Holocaust Remembrance Day, the global day of commemoration established by the United Nations in 2005.
In Berlin, the German parliament convened Thursday for a special session commemorating the victims of the Holocaust.
Parliamentary President Norbert Lammert told lawmakers that it is the duty of later generations to keep alive the memory of those murdered by German Nazis. For the first time, a survivor representing Sinti and Roma, or Gypsies, addressed the body, reminding lawmakers of what he called the "forgotten Holocaust" against 500,000 of his people.
Political prisoners, Poles, gays and lesbians and Jehovah's witnesses were also killed en masse by the Nazis, along with nearly six million Jews.
"To label people as unworthy and order their destruction and, finally, to systematically murder millions in an industrialized fashion -- that is unique in human history," Lammert said. "The memory of those events and aberrations obliges us to respect all people equally ... and to confront violations of human rights in Germany and everywhere else in the world."
Separate ceremonies were held elsewhere in Germany, including at the Buchenwald concentration camp, where elderly survivors gathered, and at a new memorial in the former factory of the company that made the crematoria ovens for the death camp at Auschwitz-Birkenau.
Nazi Germany opened Auschwitz as a concentration camp in the summer of 1940 after it invaded and occupied Poland. Its first prisoners were Poles. Because of its location in the heart of Europe, Germany soon turned it into a center for implementing the "Final Solution," the plan to kill Europe's Jews.
By the time of its liberation by the Soviet army on Jan. 27, 1945, at least 1.1 million people had died in the gas chambers at Auschwitz-Birkenau or from starvation, disease and forced labor.