Salem’s Peabody Essex Museum has announced the opening of a new 120,000-square-foot facility in Rowley to house its collection. “The completion of the new Collection Center constitutes a major milestone in the museum’s 219-year history,’’ PEM director Dan Monroe said in a statement. The center will provide space for 1.8 million artworks, several hundred thousand books, and a linear mile of archival material. The books and archives belong to the museum’s Phillips Library. Its removal from Salem elicited protests by residents earlier this year. PEM also announced that gifts and pledges to its $650 million Connect Campaign fund-raising effort have passed the $600 million mark.