it's your tv, take it with you. with directv and at&t, stream live tv anywhere data-free. join directv today starting at $35 a month. no extra monthly fees. tonight, all eyes will be on the capitol when the president makes his address to the joint session of congress. beyond the politics, what about the building that he will be in? if you have never been, the u.s. capitol is real work of art. nblz's matt lauer got a rare behind the scenes tour under the dome to learn the secrets of the capitol. >> from inaugurations. >> the only thing we have to fear is fear itself. >> reporter: to funerals.