President Obama attends 9/11 museum ceremony in New York

President Obama spoke at the opening ceremony of the long-delayed National September 11 Memorial Museum on Thursday, invoking the memory of those killed in the 2001 terrorist attacks.

The dedication ceremony in New York was attended by current and former politicians, including former President Clinton and former Secretary of State Hillary Rodham Clinton; former New York Mayors Michael Bloomberg and Rudolph Giuliani; current Mayor Bill de Blasio; and Govs. Chris Christie of New Jersey and Andrew Cuomo of New York.

“Like the great wall and bedrock that embrace us today, nothing can ever break us. Nothing can change who we are as Americans,” Obama said.

The president was joined by First Lady Michelle Obama in a tour of the museum, which is scheduled to open on May 21.

Delays have troubled the museum for months, with local officials clashing over who will shoulder the cost. Museum representatives have stated that the entire project costs about $700 million and that its operations will be about $63 million.

The museum site has relied largely on private donations, and the museum is expected to charge a $24 general admission fee. The memorial portion of the site opened in 2011 on the 10th anniversary of the Sept. 11 terrorist attacks

On Thursday, in the museum’s large underground hall, Obama spoke about the heroism of individuals on 9/11. The president paid tribute to the late Welles Crowther, a 24-year-old financial professional who is credited with saving lives before he died in the World Trade Center attacks.

The museum features artifacts from the 2001 attacks, including fragments of the airplanes used to take down the Twin Towers. The museum’s primary entryway was designed by the firm Snohetta; the below-ground museum’s lead designer was the firm Davis Brody Bond.

[Updated: A previous version of this post incorrectly stated that the firm Snohetta designed the museum. The firm designed the museum’s primary entryway.]