Nearly 13 years after al-Qaida attacked the United States, a museum and memorial dedicated to what happened that day is opening today.
President Barack Obama and other dignitaries, as well as survivors, rescue workers and family members of the victims, joined today to dedicate the museum.
Before the museum opens to the public on May 21, there will a six-day, 24-hour-a-day period when members of the 9/11 community will have exclusive access to the museum.
During that time, more family members of the victims, as well as first responders from agencies that lost members in the attacks, along with survivors and residents and business owners from lower Manhattan will be able to visit.
The formal title is the National September 11 Memorial & Museum, and it's not without controversy. It includes an exhibit that explains the rise of radical Islam that gave rise to al-Qaida.
This segment aired on May 15, 2014.