NEW YORK (AP) — The new National September 11 Memorial Museum and the memorial plaza that opened in 2011 were built for $700 million in donations and tax dollars.
Its leaders see the project as a monument to unity and resilience.
Work on the museum was initially marked by construction problems.
There also were financial squabbles and disputes over its content and the appropriate way to honor the dead.
Its opening is prompting reflection from world figures and the everyday people whose lives were changed by the attacks.