[music] Hello everyone, I'm Koi Wire and welcome to a special edition of [music] CNN 10.

Today marks 25 years since one of the darkest days in United States history, September 11th, 2001.

A quarter century has passed since coordinated terrorist attacks shocked the nation, changed America and the world forever.

Today, US President Donald Trump will honor those who died by attending a memorial at the Pentagon.

Vice President JD Vance and Second Lady Usha Vance will travel to ground zero in New York City where the Twin Towers once stood.

There, as they do every year at the National September 11th Memorial and Museum, friends and family members will read aloud the names of all 2,977 people killed in the attacks.

Parents, children, brothers and sisters, friends, and co-workers, each one with a story.

Later in the show, we'll speak with one of the architects who brought meaning to the solemn space, including something hidden in plain sight.

But first, we will reflect on this day as it unfolded 25 years ago.

We're going to take you back to CNN's coverage as these events unfolded.

Moment by moment, you'll hear the confusion and anguish as reports of what some initially believed might have been a terrible accident gave way to the realization that America was under attack.

This [music] just in, you were looking at obviously a very disturbing live shot there.

That is the World Trade Center.

And we have unconfirmed reports this morning that a plane has crashed into one of the towers of the World Trade Center.

>> The plane just uh was was uh coming in low and the t wing tips tilted [music] back and forth and then it it flattened out.

It looks like it's uh hit at a slight angle into the World Trade [music] Center.

>> I'd say the hole takes about That's our sixth, seven floors were taken out and there's more explosions right now.

Hold on.

People are running.

Listen, >> hold on just a moment.

We got an explosion inside.

>> The building is exploding right now.

You got people running up the street.

>> Okay.

I'm sorry, Wendy.

He's not an election.

>> Today, we've had a national tragedy.

Two airplanes have crashed into the World Trade Center in an apparent [music] terrorist attack on our country.

I have spoken to the vice president, to the governor of New York, to the director [music] of the FBI, and have ordered that the full resources of the federal government go to help the victims and their families and the and to [music] conduct a full-scale investigation to hunt down and to find those folks who [music] committed this act.

have a report now that the it was a plane that crashed into the Pentagon and we have a large fire at the Pentagon.

The Pentagon is being evacuated.

go.

We have a report now that a large plane crashed this [music] morning uh north of the Somerset County Airport, which is in western Pennsylvania, not too terribly far from Pittsburgh.

[music] We don't know if this is somehow connected to what has gone on in New York and Washington, but we do know that another plane has crashed, this one about 80 miles south of Pittsburgh, or at least to the southeast of Pittsburgh.

You can see [music] perhaps the second tower, the front tower, the top portion of which is collapsing.

Good lord, there are no words.

America faced some extraordinary questions in the aftermath of the attacks.

What should rise from the place where the Twin Towers fell?

How should lives be honored and remembered?

In 2003, the Lower Manhattan Development Corporation launched an international competition to design a permanent memorial at the World Trade Center site.

More than 5,200 designs poured in from around the world.

But the memorial that ultimately emerged contained an extraordinary idea called meaningful adjacencies, a way of arranging the names that reveal connections.

Co-workers beside co-workers, friends beside friends, first responders alongside those with whom they served.

Some connections are obvious, others deeply personal, relationships that a visitor might never otherwise know existed.

Today, we're taking a closer look at the remarkable thought behind this memorial and how a place holding nearly 3,000 names can still make room for nearly 3,000 individual stories.

I was honored to be his wife.

I would have died for him.

If it if they thought they were going to build over dead people, they would keep taking me with them.

>> Today, the 9/11 memorial at ground zero draws millions of visitors annually.

But in the immediate aftermath of the attacks, public opinion was divided over the site's future.

Some pushed to rebuild where the tower stood, while others fought [music] to preserve the site where thousands died.

Among them was Monica Iiken Murphy, who lost her husband on 911 and became a leading voice in establishing [music] the memorial.

>> She says she watched on television as a plane hit the second [music] tower, the tower where her husband Michael worked on the 84th floor.

I knew he was gone.

I just I knew it.

When you have a soul connection with someone, your brain says you're going to look for him.

He could be a John Doe, but your heart knows.

As soon as recovery was out, they were talking about rebuilding back.

And I was like, there's no way they're going to build up with that.

And they said, "Oh, Monica, this is prime real estate.

You we're not we can't make this anything but build building." At the end of the day, we we fought for every square inch of this memorial and I it's it took 10 years, you know, to get it done, but we and it was a lot of fighting in between.

The design ultimately [music] selected for the memorial, reflecting absence, was created by architect Michael Arod and landscape architect Peter Walker.

The arrangement of names is called meaningful adjacencies.

A flow of names that links [music] co-workers to their friends.

Places plane seatmates near each other.

First responders among the people who they were believed to be trying to save.

Amanda Sax [music] Mangold was the architect who collaborated with Michael Arod and spent years meticulously arranging the names around the pools.

What was the reasoning?

like why alphabetical order wasn't the way to organize those nearly 3,000 names.

Why?

Why was that?

>> Um there were a few reasons.

The first reason for not wanting to do it alphabetically was simply because of the repetition of last names.

There were 11 Murphy's, two Patrick Murphy's.

There were nine Kelly's, 12 Lynches.

There were two people that shared a name, Michael Francis Lynch.

two people, two distinct people.

When you start organizing by alphabetical order, you lose um the individuality of people.

And that was very important.

It was >> Sax Mangold conducted extensive research, speaking with people by phone, searching online, and contacting organizations to determine how victims knew one another and whose names should be placed together.

And what was that like for you personally hearing some of those stories and and fielding some of those requests?

>> It was emotional.

It was hard and there were many sort of let's say naysayers who didn't believe it was possible.

There was a feeling that it wouldn't be feasible to do without um technological help.

I mean obviously we work digitally as well but we organized it with our human brains.

You know, these are human stories and um they were done by by humans as well.

The structure of names also allows for a gathering of those mourning.

So, the loved ones of a victim who visit the memorial can be nearby other grieving loved ones who are only a degree or two of separation away.

>> My name is James Daell.

I'm a lieutenant on the FDMY and I'm the son of Kevin Dell who was one of the 343 New York City firemen killed on September 11th.

The crew and the people that my father responded here with uh they're all next to each other.

Them all together it just you know it that's how I remember them.

I just remember them all being together.

I remember them sitting around the table um laughing with each other.

So when I come here and I see those names in the same, you know, next to each other, just like they were sitting around a kitchen table, uh, you know, there's definitely a sense of uh resolve there, I think it's it's a true testament to to who they were and how they got here and how they died.

So I think it's fitting.

This is a sacred and hallowed space and that's why it's so important.

Um that we make sure that people understand how amazing this memorial is and how you know the fight was worth it because I don't have him today but I have him here.

>> 25 years can sound like a long time but for those who lost someone on September 11th for those who survived and for the first responders who ran toward danger 25 years may not feel very long at all.

Every year on this day, we hear two words, never forget.

But what does that really ask of us?

As the years pass, perhaps it means memories don't have to fade.

Learn the history.

Listen to the stories.

Honor not only those people who died, but how they lived, and then pass those stories forward.

I'm Koi Wire.

Thank you for remembering with us and joining us on this special edition of CNN 10.

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