The Peabody Essex Museum is hours away from entering a new era when the 220-year-old institution cuts a ribbon on its $125 million wing on Saturday, Sept. 28 at 10 a.m.

At that time, the PEM’s executive director, Brian Kennedy, Salem Mayor Kim Driscoll, museum staff, community leaders and children will perform the ceremonial duty, officially opening the new wing to the public. Everyone is invited to attend.

To mark the Salem museum’s new chapter, general admission on Saturday and Sunday is free. Alongside touring the new wing, visitors are encouraged to enjoy live music, art making and performances on both days.

Kennedy, whose directorship began three months ago, said the wing’s opening comes after “extraordinary growth” over the 26-year tenure of his predecessor, Dan Monroe, who retired earlier in the year.

“It has been truly remarkable,” he said of the museum’s growth in a recent press preview. “I don’t think there is a precedent in American museums – in terms of growth in a 25-year period. The PEM is now one of the largest museums in the country outside a big city.”

The 40,000-square-foot wing, constructed over just shy of three years, adds 15,000-square-feet of new gallery space dedicated to maritime art, Asian export and fashion and design across three floors.

Kennedy said the galleries offer “a whole new window on the world.”

Curators pulled pieces showcased in the three state-of-the-art galleries from the museum’s eclectic, worldly collection of 1.8 million objects. They are presented in new and re-imagined ways - ways that include engaging senses beyond just sight.

For locals and history buffs the new maritime art gallery on the new wing’s first floor is not to be missed. Also falling in this local-interest category: “The Creative Legacy of Nathaniel Hawthorne: Selections from the Phillips Library Collection.”

The latter is the first exhibition in a new gallery dedicated to showcasing works from the museum’s research library.

“We have a beautiful new garden which of course goes with the many among the PEM’s 22 historic properties,” said Kennedy.

The new 5,000-square-foot garden, designed by Nelson Byrd Woltz, features an eloquent water fountain and benches, offering a calm oasis in the middle of downtown Salem. Other stand-out features include a light-filled atrium and new linkages to the museum’s existing galleries.

Founded in 1799, Kennedy said the PEM is unique “by any definition, by any description,” and the new wing adds to that sentiment.

“It has a particular, special place among American museums and not just because it’s the oldest continuously operating museum in the country,” he said.