But countertenor Anthony Roth Costanzo, the avant-garde opera star hired last year to run Opera Philadelphia, is leading an effort to let the public again enjoy the Wanamaker Organ, a National Historic Landmark-designated treasure. The organ boasts more than 28,000 wood and metal pipes hidden behind a soaring wall of gold-leaf pipes that frame the building’s seven-story marble atrium.

Costanzo, with $1 million in philanthropic funding, is organizing a series of public performances this fall — including opera, ballet, theater and drag — before renovations begin next year on the building’s conversion to a retail and residential hub. The Wanamaker Organ will be featured in the first event, set for Sunday, Sept. 7, but perhaps not all of them.

“John Wanamaker, when he built this Grand Court, said he wanted it to be the intersection of arts and commerce, and that’s why he put the world’s largest pipe organ into it,” Costanzo told The Associated Press in an onsite interview Thursday evening.

“This space is operatic,” he said. “So I thought it was a perfect umbrella to bring in every arts organization I could, and all these different collaborators.”

The organ was made for the 1904 World’s Fair in St. Louis. Wanamaker, a successful merchant and civic leader, had it moved to his new emporium next to City Hall in 1909 and then hired a crew of 40 pipe makers to enlarge it so the sound filled the vast space. A decade later, famed conductor Leopold Anthony Stokowski performed there with the Philadelphia Orchestra as 15,000 people crowded into the great hall and mezzanines.

With the merchandise now gone, the acoustics rival those of the great cathedrals, Costanzo said.

“The organ for the first time is in perfect cathedral acoustic condition, so it will be the best way to hear this instrument in the history of the space, because there’s actually nothing in there,” he said.

The building’s new owner hopes to continue to incorporate art and culture into their plans, which include retail on the lower floors and office and residential space above. The organ adds opportunity, but also unique challenges.

“You’ve got this organ music going in the grand atrium, but meanwhile you’ve got other uses on these upper floors looking into that space, so you have to figure out how to make that work for everybody,” said Jon McMillan, a senior vice president of TF Cornerstone, the New York-based development firm.

Local civic groups, in an announcement Friday, said they hope to raise funds to bring back one of the city’s most beloved annual events, a holiday light show that drew generations of families to the store.

Costanzo, who continues to perform around the world, believes he can build enthusiasm for the arts by bringing it to the places where people gather, including the Wanamaker Building. And he hopes that, in turn, will help people find a way to connect with each other.

“This space is so deeply embedded in the emotion of Philadelphia,” Costanzo said. “I want them to come to Wanamaker and discover something they’ve never seen before.”