>> alice greenwald: yes.pression will be that you are surrounded by nearly 3,000 faces. >> stahl: these are the photographs that will cover those walls. look at those faces. look at all those faces. >> alice greenwald: they're ages two and a half to 85, from over 90 countries, every sector of the economy, every possible ethnic group. >> stahl: visitors will be able to search these interactive tables and call up profiles of each person, with photos and recorded remembrances by family members and friends like this one by the father of paul acquaviva, who died in tower 1. >> mr. acquaviva: he never had a bad word, literally, to say about anybody. he always looked at the positive. you know, i know, to be honest with you, he didn't get it from me because i'm very critical at times. to me, that was one of the most important things about paul. >> alice greenwald: some of them are funny. some of them are sweet. and we're not telling you who they are; their loved ones are telling you who they are. >> stahl: visitors c