DALLAS - Several events across the Dallas-Fort Worth area will mark 20 years since the Sept. 11 attacks.
While they may bring up difficult and painful memories for those who can remember exactly what they were doing when the World Trade Center's twin towers fell 20 years ago, the memorials are serving as important history lessons for those who weren't even born yet.
CONTINUED COVERAGE: Sept. 11 Terror Attacks
Students at Pinkston High School in Dallas remember the heroes who lost their lives on 9/11.
On Friday, members of the ROTC program at Pinkston High School paid tribute to first responders at the school’s flagpole.
Dallas firefighters and military members took part in the annual ceremony. The students said it’s important to honor the everyday heroes who risk their lives while remembering those who died on 9/11.
Grapevine High School students who weren't alive when planes hit the twin towers learn about the importance of 9/11 by climbing 1,980 steps.
Students at Grapevine High School, who were not even born on the day of the attacks, honored those who died with a tribute climb hosted by the school’s wrestling team.
School athletes, police officers, firefighters and others climbed 1,980 steps, which is the same number of steps in the 110-stories of the twin towers.
The head wrestling coach put the event together so the kids can understand how important it is.
"I remember when I was in college and 9/11 happened. And it just kinda hits different when you see it. I want to make sure these high school kids understand the importance because they weren’t around when this happened," said Matt Criner, a teacher and wrestling coach at Grapevine High School.
In addition to climbing the stairs, some members of the wrestling team and some first responders carried weighted vests or backpacks to simulate the weight carried by those on 9/11.
2,977 flags were placed in Los Colinas to honor the victims of the 9/11 attacks.
Another memorial ceremony at the flagpole on the Southern Methodist University campus featured members of the Highland Park and University Park police departments. And in DeSoto, there was a ceremony at Fire Station 1 on Wintergreen Road.
The Las Colinas development in Irving is remembering the victims of the 9/11 attacks with 2,977 American flags placed around the flower clock at the corner of O’Conner Road and Highway 114.
Community leaders said it’s a tribute to those who lost their lives and who put their lives at risk to save others on that devastating day.
On Saturday, several 9/11 memorial events are scheduled in cities including Dallas and Mesquite in Dallas County, Plano, Prosper and Celina in Collin County and Arlington, Benbrook and Grand Prairie in Tarrant County.
There’s a new documentary out that looks back at the attacks and what went through then-President George W. Bush’s mind after he was told about a plane crashing through the World Trade Center.
Emmy award winner Jeff Daniels narrates "9/11: Inside the President’s War Room," which is streaming on Apple Plus TV.
President George W. Bush was listening to a story with a group of school children when he first learned about the attack on America.
Mr. Bush will be going to a memorial event Saturday in Shanksville, Pennsylvania. He’ll then return to the George W. Bush Presidential Library in University Park for a 9/11 event and a showing of the documentary.
The face of terrorism has evolved over the past two decades.
The United States spent the last 20 years fighting a war in Afghanistan in response to the attacks on 9/11.
The primary target was Al-Qaida and Osama Bin Laden.
Now, the FBI says they're dealing with a lot more "lone actor" attacks, which can be harder to prevent.
Ken Gray was an FBI special agent working in New Haven, Connecticut back on 9/11.
He believes changes made in response to the attack, along with the hard work by the FBI and federal partners, have prevented another large-scale terrorist attack by foreign terrorist organizations on American soil.
"We entered in Afghanistan to take out Al-Qaida, to find and locate Osama bin Laden and to kill him. We found him. He was killed," Gray said.
And while Al-Qaida" is still a concern, Gray said it’s the so-called "lone actor" that has become a big problem in recent years.
Foreign groups spread propaganda online and on social media to inspire these types of domestic attacks.
"We've seen that time and again here in the United States, San Bernardino, for instance, the The Pulse nightclub down in Orlando, Florida," Gray said. "These type of attacks are very difficult to be prepared for because the person does not do the things like receive training in funding, receive weapons, but instead they acquire those on their own and carry out their attack."
The FBI director said an expanding array of radical beliefs is increasingly inspiring domestic terrorists, including racial and ethnic ideologies, anti-government and anti-authority sentiments, conspiracy theories and personal grievances.
Gray said it’s important to keep your guard up.
"Law enforcement does not know about it beforehand. And so that kind of threat is very difficult to prepare for and to combat against," added.
Gray said our military's exit from Afghanistan could be viewed as a real boost to the fundamentalists who want to attack the United States.