President Barack Obama and other dignitaries were in attendance Thursday for an emotional dedication ceremony of the National September 11th Memorial Museum in Lower Manhattan.
Mayors Bill de Blasio, Michael Bloomberg, and Rudy Giuliani shared the stage with survivors and families who lost loved ones in the attack.
The president said the museum would help Americans remember the heroic responses to the tragedy.
"It is an honor for us to join in your memories, to recall and to reflect, but above all to reaffirm the true spirit of 9/11: Love, compassion sacrifice," Obama said.
The president also talked of heroism, highlighting the story of Welles Crowther who became known for the red bandana he wore over his face as he went into the South Tower time and again to lead people out.
"It is our greatest hope that when people come here and see Welles' red bandana they will remember how people helped each other that day. And we hope that they will be inspired to the same in ways both big and small," said Allison Crowther, Welles' mother.
At the ceremony there was no evidence of the long and sometimes contentious fight to get the museum built. Instead, the focus was on the museum's mission, telling the story of September 11, 2001.
"Walking through this museum can be difficult at times but it is impossible to leave without feeling inspired," Bloomberg said.
"What this museum does is allow us to see, is that we absolutely can affect each others' lives by what we do at a time of crisis," Giuliani said.
The museum will be open 24 hours a day for the next week so families, first responders and survivors can visit any time they want.
It officially opens to the public next Wednesday, but opening day tickets are already sold out.
The $24 admission price is raising some eyebrows.
"Especially in the initial opening when a lot of locals haven't seen it, I think it'd be valuable to make it as accessible as possible to the people that 9/11 really impacted," said one New Yorker.
"The respect is not to give the money. The respect is to go and pray and be with them," said another New Yorker.
"It's important to really commemorate and do a beautiful, beautiful job of just the way the city was able to come back together after such a horrific tragedy," added a third New Yorker.
The museum extends 70 feet underground to the Twin Towers' foundations.
Exhibits include damaged fire trucks, the survivors staircase used by hundreds to escape the burning towers, and a mangled piece of the antenna from atop the trade center.
Florence Jones, a 9/11 survivor, donated the shoes she carried while running away from the collapsing towers.
"I wanted my nieces and my nephew and every person that asked what happened to see them, and maybe understand a little bit better what it felt like to be us on that day," Jones said.
Meanwhile, some victims' families headed to nearby Zuccotti Park before the ceremony to protest the relocation of unidentified remains to the museum.
They also gathered the night before for a candlelight vigil in Lower Manhattan.
Relatives are concerned that the repository, which is located 70 feet below ground, may be prone to flooding.
While the area is off limits to the public, the repository is open to family members, but opponents said they have no plans to visit.
"I am one of the many, many families who has no intention of ever entering that museum," said Sally Regenhard, who lost her son on September 11, 2001. "For us to be down there would mean that we were endorsing this despicable plan."
Some would prefer the remains be placed in a mausoleum above ground, while others are concerned that the remains are being treated as a tourist attraction.