After 15 years, the attacks of September 11, 2001, are still fresh in the memories of many Americans.

Nearly 3,000 people in New York, Virginia, and Pennsylvania lost their lives on 9/11 in attacks carried out with hijacked airplanes by terrorists orchestrated by Osama bin Laden. As the years pass, suffering continues alongside the memorializing—among those who lost loved ones and by survivors who sustained injuries or who were forever changed by the horrific events—even as the country, and the world, changes.

On September 11, 2001, at 8:45 a.m. on a clear Tuesday morning, an American Airlines Boeing 767 loaded with 20,000 gallons of jet fuel crashed into the north tower of the World Trade Center in New York City. The impact left a gaping, burning hole near the 80th floor of the 110-story skyscraper, instantly killing hundreds of people and trapping hundreds more in higher floors. As the evacuation of the tower and its twin got underway, television cameras broadcasted live images of what initially appeared to be a freak accident. Then, 18 minutes after the first plane hit, a second Boeing 767–United Airlines Flight 175–appeared out of the sky, turned sharply toward the World Trade Center and sliced into the south tower near the 60th floor. The collision caused a massive explosion that showered burning debris over surrounding buildings and the streets below. America was under attack.

Now, the site of the New York City attacks is home to One World Trade Center, the tallest building in the Western Hemisphere, and a marker of resilience in the face of tragedy. There are also memorials near the Pentagon and in Stoystown, Pennsylvania. This summer, the last known 9/11 rescue dog, Bretagne, was put down with a patriotic ceremony to honor her role after the attacks (she had been suffering health problems). When the planes hit in 2001, she was only two years old.