We pause to remember the events of that tragic day, as well as honor the victims and the heroism of first responders.

Here are some of the lesser-known African American women scientists who have made groundbreaking impacts in their respective fields.

Spencer Stone, Alek Skarlatos and Anthony Sadler portray themselves in "The 15:17 to Paris," Clint Eastwood's retelling of how they incapacitated a crazed gunman and saved close to 600 lives on board a train in August 2015.

The home-grown terrorist responded to a Harvard reunion query by calling his current occupation as "prisoner" and his eight life sentences as "awards."

A look back at the victims of the Salem Witch Trials and the mass hysteria that led to their deaths.

David Berkowitz, who became known as Son of Sam, went on a murderous rampage in New York City during the 1970s, taunting and insulting police, until they captured him.

The 1848 historic event triggered the women's rights movement in America.

In the HISTORY series “American Ripper,” the great-great-grandson of H.H. Holmes claims “America’s First Serial Killer” was London’s notorious “Jack the Ripper.”

The historic uprising at the Stonewall Inn in Greenwich Village sparked the modern LGBT rights movement in the U.S.