Bill Clinton, Elie Wiesel Join Holocaust Survivors to Commemorate Museum's 20th Anniversary

For 20 years, the U.S. Holocaust Memorial Museum has reminded visitors of atrocity, grief and survival.

On Monday, nearly 4,000 supporters joined 843 Holocaust survivors and 130 veterans to celebrate its 20 th anniversary and hear speeches from President Bill Clinton and museum founding chairman Elie Wiesel. Under a large tent outside the museum, just south of the National Mall in Washington, D.C., survivors talked with American soldiers who liberated concentration camps, sharing their stories.

Ernest Gross, who survived the Dachau concentration camp, searched for years to find a camp liberator. He found one in Don Greenbaum of Philadelphia. The two traveled to Washington to attend the ceremony together.

"I was transported from Camp 7 to Dachau to be gassed and to go into the ovens," Gross told ABC News just before the ceremony, from his seat next to Greenbaum.

"I was standing in line, and I was close enough that I was able to see the ovens, and all of a sudden I see the German soldiers are throwing their weapons down," Gross said. "I didn't know why I turned around, and I saw the American Army liberating the camp, and for 67 years I looked for somebody who liberated me to thank him."

President Bill Clinton warned that the roots of the Holocaust are "alive and well" today.

"Most of us spend 99 and a half percent of our time thinking about the half a percent of us that is different from everybody else, and that makes us vulnerable to the fever and the sickness that the Nazis gave to the Germans," Clinton said.

"That sickness is very alive all across the world today," he added. "Pick a target, as long as they're not you, it's OK. That's what led that beautiful Pakistani girl Malala to get shot just because she wanted to go to school, because it threatened a group whose power rests in no small measure on its ability to control women's lives.

"It is still the major cause of heartbreak around the world, as we saw in Boston at the marathon, and it is still the biggest threat to our children and grandchildren reaping the full promise of an interdependent world," he said. "You know the truth, you have enshrined it here, you must continue to work to give it to all who would come."

Wiesel told the audience that the museum's purpose is as much to serve future generations as it is for those who lived through the Holocaust.

"I say to young people, 'You are our hope. Whatever we do now is not only for the sake of the past, but surely also for the sake of the future, and you are our future,'" Wiesel said.

Holocaust survivors in attendance predicted that today's anniversary will be the last major gathering of survivors, many of them in their 80s and 90s, interned in concentration camps 70 years ago.

"Maybe some of the Holocaust deniers will stop this nonsense," said Rose Schindler, a Czech woman who survived Auschwitz.

"This is gonna be the last reunion of the Holocaust people because most of us can't travel anymore," Schindler said. "Nobody's under 85, 90."