Moment of Slience Falls on Ground Zero

The World Trade Center site fell silent four times - twice each to mark jetliner crashes and the collapse of its iconic towers - and solemn remembrances were held around the nation Monday to mark the fifth anniversary of the Sept. 11 terrorist attacks.

At ground zero, a cavernous pit still largely unchanged from the first anniversary, family members of the 2,749 people lost held photos of loved ones, crossed themselves and sobbed quietly.

The 16-acre site went quiet at 8:46 a.m. and 9:03 a.m., the moments American Airlines Flight 11 and United Flight 175 hit, and again at 9:59 a.m. and 10:29 a.m., when the south and north towers fell.