15 years later, and the world has not forgotten.

By Jess McHugh
September 12, 2016
Round-up of 9/11 memorials
Credit: Getty Images

Throughout the country and in major cities around the world, people gathered Sunday to commemorate the lives of those who died 15 years ago during the attacks on Sept. 11, 2001.

After terrorists hijacked four commercial planes and crashed them into the Twin Towers in New York, the Pentagon outside of Washington D.C., and a field in rural Pennsylvania, nearly 3,000 people perished in what became the worst terror attack on U.S. soil.

Families of the victims, as well as residents of the city, gathered at the 9/11 memorial in New York to pay their respects. On the site where the towers once stood, the names of the thousands of dead were read aloud as bagpipes played. Other memorial events, including church services at St. Patrick’s Cathedral, took place across the city.

"There is no New Yorker who somehow evaded the pain of that day. We all felt it. We all were affected. Everyone felt it. Everyone suffered,” Mayor Bill de Blasio said at the services at St. Patrick’s Cathedral.

At a ceremony at the Pentagon in Washington D.C. President Barack Obama urged unity among U.S. residents and described the nation’s diversity as its greatest asset. “As Americans, we do not give into fear,” Obama said, the Washington Post reported. “We will preserve our freedoms, a way of life that makes us a beacon to the world.”

The fourth plane that was hijacked by terrorists never made it to its intended destination—which was likely the White House or the Capitol—after passengers staged a rebellion. Instead the plane crashed into an empty field in rural Pennsylvania where all 40 passengers perished. Firefighters, emergency workers and families of the victims of Flight 93 marked the day with a ceremony at the recently created memorial on the site of the crash.

Commemorations were not limited to the U.S. alone. 9/11 was an event that reverberated throughout the world, and international cities have marked it accordingly. Ceremonies in Dublin, Glasgow, London and Rome, among others, marked the day while paying tribute to local firefighters and first responders.