Silverstein's spokesperson noted surprise that the suit was filed as the developer believed an agreement to mediate the claim had been reached. "It has always been our desire to avoid a senseless courtroom fight," the statement reads. "Daniel Libeskind has already been paid many millions of dollars for his work by the LMDC and the Port Authority and is unable to provide any industry standard timesheets or other documentation that would justify an additional payment of more than $800,000."

Last July, an "historic collaboration" was announced between Skidmore Owings & Merrill, a firm handpicked by Silverstein, and Studio Daniel Libeskind to design the world's tallest building at the World Trade Center site. Libeskind is suing for funds associated with that collaborative effort. Libeskind had been designated by the Port Authority of New York and New Jersey as the master plan architect for the site, beating out seven other architectural teams.