Tom Lenahan worked for American Express 24 years ago, one of about 4,000 employees at the corporate headquarters in and near the World Trade Center. Running late on September 11, Lenahan was directly below when United Airlines flight 175 hit the south tower at 9:03 that morning in 2001. Ducking under an overpass for cover, Lenahan sheltered briefly there with two others, trying unsuccessfully to get them to leave before that structure also collapsed. The stories of those who lived through that day will surely continue to be told, at least by those for whom it is an act of healing. How subsequent generations remember the attacks will be judged by historians.