Why the Towers Fell is a special episode of NOVA scheduled for broadcast on PBS on April 30, 2002. This online material complements the television program by assessing the exact cause of the disaster from an engineer's standpoint. One section of the Web site is an interview with a materials engineering professor from the Massachusetts Institute of Technology. In the dialog, he describes the most probable reasons for the towers' collapse and some building safety improvements that can be made in the future. There are two multimedia features on the site: one explores the structure of metal while the other looks at firefighter equipment. A particularly moving account of the Trade Center collapse comprises another section, from one of only four people who escaped from above the floors where either plane hit.