Last year, the National Geographic Channel presented the most excellent documentary about the September 11th atrocities called "Inside 9/11."
Tonight, Sunday August 27, they present an updated two hour program with limited interuption at 7PM EST. Check your local schedule for times. The program may also repeat if you miss tonight's presentation.
National Geographic will be showing a number of new documentaries on terrorism all this week.
See Catherine Seipp's conservative viewing guide for this program here.