NEW YORK (AP) — An agreement on the completion of the Sept. 11 museum at Ground Zero has been reached a day before the 11th anniversary of the terror attacks.

The agreement between the Port Authority of New York and the foundation that controls the National September 11 Memorial was announced Monday. The Port Authority owns the World Trade Center site. The museum was supposed to open this month, but construction all but ceased a year ago because of a funding squabble. between the foundation and the Port Authority.

The underground museum is to house such artifacts as the staircase workers used to escape the attacks.

The memorial includes a plaza where waterfalls fill the fallen towers’ footprints. It opened last year and has attracted millions of visitors.