Twenty-five years after two hijacked planes brought down the World Trade Center in clouds of dust, Lower Manhattan is thriving. The Financial District is now FiDi, with twice as many residents, and new bars and restaurants in a neighborhood that once closed up when Wall Street’s trading day ended. The observatory at the rebuilt One World Trade Center looks out over New York City from the country’s tallest building, its height a symbolic 1776 feet. The 9/11 Memorial & Museum draws about 9,000 people a day. 

At the Pentagon, more than one million people visit its outdoor memorial each year: 184 benches over pools of water, placed in the path of the third hijacked plane.

Near the field where the fourth plane crashed outside Shanksville, Pennsylvania, the passengers are honored with a white marble wall of names. The motto is: “A common field one day, a field of honor forever.”

The country will come together on Friday over a shared national tragedy, but other changes remain controversial.

The U.S. went to war in Afghanistan and Iraq, and both conflicts defied quick military victories. Protests follow the Department of Homeland Security and its agency, ICE, created after Sept. 11, over the tactics used toward migrants and refugees. Then-President George W. Bush claimed expanded powers for the presidency including military tribunals and harsh interrogation methods that critics call torture and that have thwarted prosecutors.

Osama bin Laden, the al-Qaida founder angry over U.S. foreign policy, was killed in a raid on Pakistan, but the man accused of being the mastermind, Khalid Sheikh Mohammed, remains imprisoned at the U.S. Navy base in Guantanamo Bay, Cuba. A military judge has ruled that his confessions to F.B.I. agents could not used against him because they were not made voluntarily. Mohammed was waterboarded in 183 rounds while he was held earlier in secret C.I.A. prisons. His trial date is now set for June 5, 2028.

How the 9/11 attacks unfolded

On the morning of Sept. 11, 2001, 19 men hijacked four commercial planes bound for California from Boston, Newark, New Jersey, and Washington, D.C. Two of the planes, American Airlines Flight 11 and United Flight 175, departed from Boston, headed to Los Angeles. Each plane had five hijackers aboard. At Washington Dulles International Airport, another five hijackers boarded American Airlines 77, also bound for Los Angeles. The last flight, San Francisco-bound United Airlines Flight 93, left from Newark International Airport with four hijackers on board.

Two of the planes flew into the World Trade Center’s Twin Towers, the third caused a portion of one of the Pentagon’s rings to collapse and the fourth crashed into a field outside Shanksville after passengers stormed the cockpit. 

Fifteen of the al-Qaida hijackers were from Saudi Arabia. The others were from Egypt, Lebanon and the United Arab Emirates. 

Source: 9/11 Memorial and Museum

How to honor 9/11 victims

9/11 victims

Nearly 3,000 people died in the Sept. 11 attacks, most at the World Trade Center. The youngest was 2 1/2 , one of eight children killed.

The remains of more than 1,600 victims in New York City have been identified, leaving 40 percent of those who died unidentified. In August, a woman was identified using a new method, a combination of DNA analysis and research involving public genealogy databases.

People continue to die from Sept. 11-related diseases, from cancers, respiratory illnesses and others. More than 152,000 people have enrolled in the federal World Trade Center Health Program.

Here are the victims.

9/11 before and after photos

9/11 before and after

Twenty-five years later, the World Trade Center has mostly been rebuilt, four skyscrapers and 2 World Trade Center under construction. The Pentagon was repaired in less than a year. Take a look at the aftermath of the attacks and how the sites look today.

Following the fallout 25 years later

NBC Local stations across the U.S. have been reporting on how the Sept. 11 attacks transformed the country in the quarter century since.

Families reflect on how their lives were changed. First responders and others are struggling with Sept. 11-related illness. New documents are calling into question reassurances that New Yorkers received about the safety of the air after the World Trade Center fell.

Here are some of those stories.

How ‘Hope’ endures decades after 9/11 attacks

This week marks 25 years since the September 11 attacks changed New York City forever. In the decades since, we’ve seen tragedy and heartbreak, but also grit and resilience. NBC New York’s Andrew Siff shares one family’s full-circle moment.

The 25 years since the attacks have brought tragedy and heartbreak, but also grit and resilience. NBC New York’s Andrew Siff shares one family’s full-circle moment.

FDNY releases report on impact of 9/11 on first responders’ health in years since attacks

The FDNY released a landmark report on the 9/11 attacks and their impact on first responders in the years that have followed. The report builds on the existing research and brings it up to date, 25 years later. FDNY researchers have monitored first responder medical questionnaires and exams, studied conditions that developed as a result of 9/11, and explored any emerging conditions to see if they could be related. NBC New York’s Rana Novini reports.

The FDNY released a landmark report on the Sept. 11 terror attacks and the impact on first responders’ health in the 25 years that have followed.

The report follows the physical and mental health of 15,000 EMS providers and firefighters who were exposed to the air at the World Trade Center in the aftermath of the attack. While the devastating health impacts to first responders at Ground Zero have been known for years, the report builds on existing research and brings it up to date, 25 years later.

The report shows more than 12,000 have been diagnosed and certified with at least one related physical or mental health condition.

Read the full story from NBC New York’s Rana Novini.

Why 9/11 and its many griefs land differently 25 years later

Crystal (L) and Jordan Tirado view September 11th missing person posters August 22, 2002, in New York City. The posters were still attached to a wall outside Saint Vincent's Hospital.

Photo by Mario Tama/Getty ImagesPhoto by Mario Tama/Getty Images

Crystal (L) and Jordan Tirado view Sept. 11 missing person posters August 22, 2002, in New York City. The posters were still attached to a wall outside Saint Vincent’s Hospital nearly a year after the attacks.

Trove of new 9/11 docs suggest NYC officials knew of air quality health risks

It’s been a quarter century since the September 11 terror attacks and tri-state families are still losing loved ones who died with 9/11-related illnesses. On Monday, a wake was held for former FDNY Lieutenant Gerard Reilly. NBC New York’s Chris Glorioso reports.

In the same week that the country is marking the 25th anniversary of the attacks, New York City released about 170,000 pages of documents related to post-9/11 air quality and health risks — a trove of paperwork within which some notes suggest city officials knew of the potential environmental dangers and legal exposure in the fairly early aftermath of the terror attacks.

One undated internal document — a letter to former Mayor Rudy Giuliani’s deputy mayor, Robert Harding — listed various potential grounds for lawsuits against the city, including health advisories that caused people to return to the area too soon, causing toxic exposure, rescue workers being provided with faulty equipment, and police failing to secure businesses from looters.

Another memo early in the Michael Bloomberg administration, five months after 9/11, said the city was “leaving itself open to a barrage of lawsuits. At the least, we should discontinue telling people to clean their apartments with wet mops and rags.” The note added that the city should ask the federal government for cleanup funds.

Read the story on NBCNewYork.com.

Dispatcher recalls first reports about Pentagon on 9/11

A police officer who first spotted American Airlines Flight 77 just seconds before it hit the Pentagon Sept. 11, 2001, radioed what he saw to dispatcher Kyra Pulliam. News4’s Paul Wagner spoke with her.

A police officer who spotted American Airlines Flight 77 just seconds before it hit the Pentagon radioed what he saw to dispatcher Kyra Pulliam. NBC Washington’s Paul Wagner spoke with her.

How the National Cathedral played a pivotal role in honoring 9/11 victims

Three days after 9/11, President Bush gathered rescue workers and military members for a prayer service at the National Cathedral. For the first time, we’re hearing from one of the reverends who made that service possible. News4’s Aimee Cho reports.

Three days after the Sept. 11 terrorist attacks, President George W. Bush gathered rescue workers and military members for a prayer service at Washington National Cathedral. For the first time, we’re hearing from one of the reverends who made that service possible.

The service honored the stories of sacrifice and acknowledged the grief that engulfed the nation in the wake of Sept. 11.

“Inside the World Trade Center, one man who could have saved himself stayed until the end at the side of his quadriplegic friend,” President George W. Bush said during the service.

Read the story from NBC Washington’s Aimee Cho.

‘Locking the doors and losing the aircraft’: Inside Reagan National Airport on 9/11 and its aftermath

Chris Browne, who was in charge of Reagan National Airport on 9/11, spoke with News4 about that day and what has stuck with him 25 years later.

It’s been a nearly quarter century since 9/11, but the magnitude is still fresh on the minds of those who were right there.

“I turned to my colleague and said, ‘This is a terrorist incident. We’re in this,'” recalls Chris Browne, who was the manager of Washington Reagan National Airport at the time.

Browne, now the director of the National Air and Space Museum and a former naval pilot, says he knew immediately that it was a terrorist incident. By the time the world was watching live on TV, a second plane was headed for the World Trade Center.

Read the story from NBC Washington’s Adam Tuss.

Curated and compiled by Noreen O’Donnell & Nelson Hsu.