She and her husband, Fred, who survived the Holocaust in Holland as a child by being hidden and passed from house to house, wanted to be part of the last large reunion of survivors.
"In 10 more years, most of us will be gone," Greenwood said, noting the museum is a way to keep their stories alive.
Herman Zeitchik, 89, of Silver Spring, Md., was a young U.S. Army soldier when his unit landed at Normandy in the mission to liberate Europe. He remembers coming across the Dachau concentration camp unexpectedly in southern Germany.
"They never told us there was a concentration camp, but we smelled it," Zeitchik said. "We smelled the burning flesh."
Later during a patrol, Zeitchik saw people held within the camp's chain-link fence. "That's the first time I knew about the concentration camps," he said.
Dachau was the first regular Nazi concentration camp, established in 1933. The Americans liberated Dachau's prisoners in 1945.
The museum continues collecting objects, photographs and other evidence of the Holocaust from survivors, veterans and archives located as far away as China and Argentina. Curators expect the collection to double in size over the next decade.
This week, the museum is opening a special, long-term exhibit titled "Some Were Neighbors: Collaboration and Complicity During the Holocaust." It includes interviews with perpetrators never shown before.
Curator Susan Bachrach said the exhibit's research challenges the idea that the Holocaust was primarily about Hitler and Nazi leaders. Surveys at the museum show that's what most visitors believe.
"That's very comforting to people, because it puts distance between the visitors and who was involved," Bachrach said.
So, the museum set out to look at ordinary people complicit in the killing and persecution of millions of Jews through greed, peer pressure, a desire for career advancement or other factors beyond hatred or anti-Semitism. The exhibit includes images of bystanders looking on as Jews were led away.
Focusing only on fanatical Nazis would be a serious misunderstanding of the Holocaust, Bloomfield said.
"The Holocaust wouldn't have been possible, first of all, without enormous indifference throughout Germany and German-occupied Europe, but also thousands of people who were, say, just doing their jobs," she said, such as a tax official who collected special taxes levied against Jews.
Much more is still being learned about the Holocaust, Bloomfield noted.
The museum is compiling an encyclopedia of all incarceration sites throughout Europe. When the project began, scholars expected to list 10,000 such sites. Now the number stands at 42,000.
Since opening, the museum has received more than 35 million visitors.
U.S. Holocaust Memorial Museum: http://www.ushmm.org
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