No matter where you lived in America on the morning of Sept. 11, 2001, the story often begins with a sapphire sky filled with airy white clouds perfectly contrasted against the expansive blue, a picture-perfect backdrop shattered by the deadliest attack on American soil in the country’s history.

Nineteen men, trained by al Qaeda, boarded four passenger aircraft that morning, seeking to carry out a devastating coordinated attack aimed at symbols of American freedom: the World Trade Center, the Capitol, and the Pentagon. Three hit their target. Flight 93, the plane targeting the Capitol, crashed in an isolated field in Somerset, Pa., thanks to brave passengers who wrested control of the plane from the hijackers. More than 3,000 people lost their lives that day, 400 of whom were New York City’s first responders.