The north tower of New York's World Trade Center collapses after being struck by hijacked American Airlines Flt. 11, Tuesday, Sept. 11, 2001.

(AP Photo Richard Drew)

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The north tower of New York's World Trade Center collapses after being struck by hijacked American Airlines Flt. 11, Tuesday, Sept. 11, 2001.

(AP Photo Richard Drew)

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Fri, Sep 9, 2011 7:29 PM EDT