What would make someone rush into a towering inferno and dash up stairs toward danger against a flow of human beings running in the opposite direction? Only someone who's been there can tell us.

Report of a team of civil, structural, and fire protection engineers, deployed by the Federal Emergency Management Agency (FEMA) and the Structural Engineering Institute of the American Society of Civil Engineers (SEI/ASCE), in association with New York City and several other Federal agencies and professional organizations, to study the performance of buildings at the WTC site following the attack of September 11, 2001.