The hauntingly beautiful music of a children's choir opened the dedication ceremony Thursday morning at the 9/11 Memorial Museum.
President Obama addressed a crowd of dignitaries that included Bill and Hillary Clinton, Governors Cuomo and Christie, and former New York City Mayors David Dinkins, Rudolph Giuliani and Michael Bloomberg.
The president said, “Here at this museum, we come together. We stand in the footprints of two towers, graced by the rush of waters. We look into the faces of 3,000 souls from all over the world. We can trace their names and hear their voices."
President Obama was deeply moved by one exhibit, a red bandanna that belonged to 9/11 hero Welles Crowther , who wore it over his face as he helped save people fleeing from the South Tower.
"After the planes hit, he put on that bandanna and made sure others made it,” said the president.
The museum contains more than 20,000 photographs and thousands of artifacts from that terrible day in American history.