WASHINGTON — Who are these people in the pictures? Why are they here?

It’s Thursday, Yom HaShoah — Holocaust Remembrance Day. I’m at the reflecting pool in front of the Lincoln Memorial. I’m looking at dozens of jumbo-sized photographs. These are portraits of Holocaust survivors, with their stories.

This “Lest We Forget” exhibition opened on Tuesday here, in one of the most iconic outdoor public spaces in the U.S.

The German Embassy partnered with German-Italian artist Luigi Toscano to bring this display to the National Mall, in cooperation with the United States Holocaust Memorial Museum.

The museum is marking its 25th anniversary this month. Alarming findings in a new survey highlight the importance of the museum — as well as the Illinois Holocaust Museum and Education Center in Skokie — and similar institutions.

OPINION

Eleven percent of adults in the U.S. — and 22 percent of millennials — haven’t heard or are not sure of if they have heard of the Holocaust. That’s according to the survey conducted for the Conference on Jewish Material Claims Against Germany.

The Nazis came to power in Germany in 1933, and with collaborators in other nations, murdered six million Jews and others — Roma, or Gypsies; homosexuals, political opponents, Jehovah’s witness, the disabled and some from Slavic countries.

Killing Jews was the Nazi priority.

Auschwitz is one of the best known of the thousands of Nazi concentration camps and ghettos. Forty-one percent of the respondents of the survey and 66 percent of millennials were unable to identify Auschwitz.

A bright spot was that 80 percent of U.S. adults said “it is important to keep teaching about the Holocaust so it doesn’t happen again.”

Which brings me back to the photographs on the Mall – and the students in Parkland, Florida.

Those photos are reminders “of the fragility of democracy,” said Diane Saltzman, the director of Survivor Affairs at the Holocaust Museum. Of what happens, she said, “if we’re not all constantly vigilant.” Twenty-three portraits are Holocaust survivors who volunteer at the museum.

The German penchant for record-keeping makes the Holocaust the most documented genocide in history. A tremendous amount of material exists. All the documents, notes Saltzman, “were created by the perpetrators themselves.”

But it’s the personal stories of survivors — their testimony to what happened — that is most important to tell, record and preserve.

Toward that end, the Illinois Holocaust Museum and Education Center, in its “Take a Stand Center” presents a holographic “Survivor Stories Experience.”

I asked Saltzman what will happen as the numbers of Holocaust survivors dwindle.

“I think it’s going to be a constant challenge. We’ll have to embrace the responsibility to continue telling their history … (and) lessons so that people understand what’s at stake when (you) don’t pay attention to these warning signs,” she said.

“… When the Holocaust survivors can no longer speak for themselves, these collections will be their voices,” Saltzman said.

A maxim of the Holocaust Museum is “Never Again: What You Do Matters.”

Never Again. A phrase strongly associated with the Holocaust.

After the shootings in Parkland, Florida, the students who survived — some were in Holocaust studies classes at the time of the murders — named the movement they launched #NeverAgain.

I asked Nadine Epstein, the Editor-in-Chief and CEO of Moment Magazine — whose co-founder was noted Holocaust author Elie Wiesel — about the students’ embrace of “Never Again” and its use in the Holocaust context.

“Elie Wiesel was not the first person to use the phrase Never Again, but he helped make it part of our lexicon,” Epstein said.

“ ‘Never again,’ becomes more than slogan,” he said. “It’s a prayer, a promise, a vow … never again the glorification of base, ugly, dark violence.”

Epstein said the students “may not all know its history, but the phrase has become part of our consciousness and is a natural response to horror, anger and grief.”

Never Again.

Said Saltzman, “The Holocaust survivors are the best teachers about what happened when hate is left to go unchecked.”