Then: A composite image of Donald Trump (left, clockwise), New York City Mayor Rudy Giuliani, Sen. Hillary Clinton, Tim Kaine, Rep. Nancy Pelosi and Rep. Tim Kaine. Getty Images and AP hide caption

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Getty Images and AP

People look out at the former site of the World Trade Center in New York City in 2005, where construction had started on Freedom Tower. Spencer Platt/Getty Images hide caption

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Spencer Platt/Getty Images

Three World Trade Center is under construction near One World Trade Center, which was completed in 2013. The new building stands 1,079 feet tall, and its topping-out ceremony was held in June. Hansi Lo Wang/NPR hide caption

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Hansi Lo Wang/NPR

In Ongoing Rebuilding Of Ground Zero, A Balance Of Remembrance, Resilience

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Bretagne, shown here at age 13, worked as a search dog at ground zero after the Sept. 11 attacks. She died Monday at 16, the last known surviving Sept. 11 search and rescue canine. Charlotte Dumas/Barcroft Media via Getty Images hide caption

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Feliciano stands at the gravesite of his wife, Rosa. "She's buried here," he says. "So Green-Wood Cemetery is ground zero for me." Courtesy of Isaac Feliciano hide caption

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Courtesy of Isaac Feliciano

At A Brooklyn Cemetery, A Place Of Work — And An Enduring Memorial

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Family members of victims of the Sept. 11 attacks demonstrate against the decision to transfer the unidentified remains to a repository at the World Trade Center site. Eric Thayer /Reuters /Landov hide caption

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Eric Thayer /Reuters /Landov

Paul Simon singing 'The Sound of Silence'

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President Obama pauses after laying a wreath at the National Sept. 11 Memorial at Ground Zero in New York, Thursday, May 5, 2011. Charles Dharapak/AP hide caption

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Charles Dharapak/AP