Pictures of WTC before and after the attacks. Photos of the attacks and the towers falling. Archived photos of WTC during construction and years before the attacks
Multiple videos of planes hitting the towers from different angles and the towers falling
Photos and commentary from a person who worked at Ground Zero in September 2001.
A web cam that looked up the street to WTC before the attacks, gives a view of the clean up work as it progressed over weeks and months. Excellent archived photos.
Paths of the planes, Impact Zones ...from the New York Times.
Download free viewer and 3D model of WTC complex