The World Trade Center's Twin Towers are gone and replaced by a towering new building, but New York City and America paused on Sept. 11 to remember and reflect the deadly terrorist attack that felled thousand in 2001.

Friends and relatives of the victims came together Thursday in three places struck by Osama Bin Laden's Al Qaeda 13 years ago to keep those fateful memories alive. They converged at Ground Zero in Lower Manhattan along with a Pennsylvania field and at the Pentagon to memorialize the event that changed the world.

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Memorials began late Wednesday with New york's skyline punctuated with two streaming blue lights even as President Obama presented his plans for additional U.S. intervention in the Middle East.

At 8:46 a.m. Thursday, the memorials continued marking 13 years to the minute when the first hijacked plane struck the north tower. The president along with Vice President Joe Biden and Michelle Obama bowed their heads on the White House lawn. The president led his memorial speech with quotes from the Bible and later laid a wreath at the Pentagon.

A second pause took place 15 minutes later to mark the second plane striking the south tower. The names of all those who died at the World Trade Center, the Pentagon and at Pennsylvania were read aloud, the only sounds punctuating the silence for an additional four minutes.

At the World Trade Center site that now houses a museum and memorial in a new building, families read aloud the names of those who perished in the attack. At the Pentagon, Defense Secretary Charles Hagel and the chairman of the Join chiefs of Staff Martin Dempsey led the memorials, accompanied by the Navy Brass Quartet.

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