NEW YORK (CNN) -- President Barack Obama marked the dedication of the long-awaited September 11 Memorial Museum Thursday with the families, survivors and rescuers at the site of the worst terrorist attack on U.S. soil.
"It is an honor for us to join in your memories, to recall and to reflect, and above all to reaffirm the true spirit of 9/11: love, compassion, sacrifice and to enshrine it forever in the heart of our nation," the President said during the ceremony.
Both chilling and somber, the memorial will take visitors back to the day the twin towers of the World Trade Center were felled by hijacked jet planes on a clear September morning nearly 13 years ago.
The ceremony was attended attended by dignitaries such as New York Gov. Andrew Cuomo, former New York mayors Michael Bloomberg and Rudolph Giuliani and relatives of the more than 2,700 people who perished at the site.
Speakers recounted stories of random acts of kindness and courage that marked the fateful day, of firefighters who died climbing up stairs to save lives, of a young man named Welles Crowther who emerged from the smoke wearing a red bandana and calmly led survivors to the stairs in one of the towers.
"They didn't know his name," Obama said. "They didn't know where he came from but they knew their lives had been saved by the man in the red bandana."
Crowther led survivors to safety during the chaos of the terrorist attack, before going back up the stairs to save others and losing his life. One of his red bandanas is on display in the museum.
"All those who come here will have a chance to know the sacrifice of a young man, who like so many, gave his life so others might live," Obama said.
The museum will open to the public May 21.
The museum and memorial plaza, which opened in 2011, were built with $700 million in donations and tax dollars following construction problems and disputes over how best to remember the thousands of lives lost that day.
The site, which has risen up from the ashes of suffering and tragedy, is expected to stand as a symbol of resilience, organizers said.
It holds some 12,500 objects, 1,995 oral histories and 580 hours of film and video.
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