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.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.”The ceremony at Auschwitz is one of several being held across the world on International Holocaust Remembrance Day. 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.