the rosalind p. walter foundation. koo and patricia yuen, committed to bridging cultural differences in our communities. barbara hope zuckerberg. we try to live in the moment, to not miss what's right in front of us. at mutual of america, we believe taking ce of tomorrow can help you make the most of today. mutual of america financial group, retirement services and investments. >> for 25 years, consumer cellular's goal has been to provide wireless service that helps people communicate and connect. we offer a variety of no-contract plans, and our u.s.-based customer service team can help find one that fits you. to learn more, visit www.consumercellular.tv. additional support has been provided by: and by the corporation for public broadcasting, a private corporation funded by the american people. and by contrutions to your pbs station from viewers like you. thank you. >> sreenivasan: good evening, and thank you for joining us. on a tuesday morning, 20 years ago today, the unimaginable unfolded. 19 terrorists, later ident