9/11 25th anniversary ceremony: Families gather at WTC, Pentagon, Shanksville

People moved out of the way on Friday in the Oculus as sunlight reflected the outline of the Twin Towers on the floor.

This is the result of an architectural feature that moves the light across the floor during the exact time of the attacks - from 8:46 a.m. to 10:28 a.m.

The design was conceptualized by master plan architect Daniel Libeskind, who took inspiration from commemorative sundials, embracing the meaningful relationship between light, remembrance, and the city around the campus.

"Permanently weaving that wedge of light into the literal foundation of the Oculus is a fitting tribute to the memory of those first moments of the attacks and to the master design vision that our redeveloped campus is built around," said Port Authority Chairman Kevin O'Toole. "Future generations will be able to follow the path of the wedge of light across the campus using these markings to connect with how the events of that day and those terrible moments in time are with us still, woven into the campus itself."

The reading of the names at the New York City ceremony concluded with powerful words from the son of victim Michael Massaroli.

"You do my dad's legacy and the legacy of all these victims no honor by using this tragedy to spread hate," he said.

"We have seen a medley of people come up today (to read victims' names), of all races, all religions, all creeds," he said.

"I've had to grow up and spend the past 25 years seeing people use (9/11) to hate on our Muslim brothers and sisters, to hate on people who don't look like them. And that's wrong and that does no honor to the victims here," he said, as the crowd applauded. "I want to use the little platform I have to ask for that to please stop."

He also thanked the dignitaries and families who stayed until the end of the reading of the names, saying every single name matters.

For the first time, the 9/11 Memorial & Museum added a seventh moment of silence at this year's ceremony to honor those who have died of illnesses related to their time at or near the World Trade Center site.

For the past 24 years, there have been six moments of silence: two to mark the times when the planes struck the World Trade Center towers; one to mark when a plane struck the Pentagon; one to mark when a plane crashed in Shanksville, Pennsylvania; and the two times the World Trade Center towers collapsed. Each moment of silence is followed by a bell toll.

This new, seventh moment of silence was observed at the conclusion of the reading of the names and will be a permanent part of the annual ceremony.

More than 9,000 people have now died from 9/11-related illnesses, approximately three times the number killed on Sept. 11, 2001, according to the World Trade Center Health Program.

Hundreds of people gathered in Shanksville, Pennsylvania, to mark the 25th anniversary of United Flight 93's crash.

The family members of the 40 passengers and crew who were killed read their names, accompanied by bells.

The color guard folded a U.S. flag and placed it on a giant rock near the edge of a grove of hemlocks. That rock is where some of the very last pieces of Flight 93 came to rest.