Families, survivors, first responders and dignitaries marked the 25th anniversary of the 9/11 attacks with somber and poignant ceremonies. That included major gatherings in New York, at the Pentagon ...

The documents illustrate security analysts' tracking of bin Laden's movements and support system, as well as concerns about possible threats to U.S. targets.

Horizons moderator William Brangham explores the long-term health impacts with Dr. Michael Crane, Dr. Benjamin Luft and John ...