Al-Zawahiri was deeply involved in the planning of 9/11, and led the organization after bin Laden was killed in 2011. He died in a U.S. drone strike in Afghanistan on Sunday.
Just hours after the Sept. 11 attacks, President George W. Bush said, "The resolve of our great nation is being tested." So here we are 20 years later. Have we passed the test?
Many children of 9/11 victims were too young to remember their parents who died. They've grown up living with the tension between having a personal connection to the day but few, if any memories.
