Disappointed and vowing to pursue stronger historic preservation protections, advocates for the Boyd Theater said Thursday that they would drop all plans to appeal a March ruling allowing the demolition of the interior of Center City's only remaining movie palace.

Preservationist Howard Haas said he and others feared their efforts would grind too slowly through the system while crews continued to dismantle the Boyd's cherished art-deco auditorium, leaving them battling, potentially, over the fate of "four walls" at 1910 Chestnut St.

Demolition began just days after the Historical Commission gave its approval on March 14.

In the settlement finalized Thursday, Haas' Friends of the Boyd joined with the Preservation Alliance for Greater Philadelphia in dropping court and administrative challenges against building owner Live Nation, developer Neal Rodin, and iPic Entertainment, the movie chain that plans to convert the site of the 1928 theater into a high-end multiplex.

Advocates accepted concessions that included a pledge to preserve artifacts such as the theater's towering art deco mirrors for placement at a museum or elsewhere; a promise to include an exhibit of the Boyd's history in the redeveloped property; and the creation of an easement, to be held by the Preservation Alliance, to protect against future efforts to alter the facade, which is being restored under the Rodin plan.

The auditorium continues to be gutted.

"It's an awful ending for the 12-year battle for the Boyd. But it mitigates things," Haas said. "We did the best we could under these terrible circumstances."

On the other side, iPic chief executive Hamid Hashemi expressed relief, and said he hoped to open the eight-screen theater-and-dining venue as early as fall 2015.

"We are thrilled that it's over," he said. "We're going to build something that everyone in Center City can be proud of."

Live Nation executives and Rodin were unavailable for comment Thursday.

The theater, closed since 2002, had been the focus of multiple failed redevelopment and preservation efforts. The vexing question always: How could a single-screen, 2,350-seat theater make money and be self-sufficient after an undoubtedly costly and complex upgrade of its profoundly deteriorated interior?

Haas said his group and the Preservation Alliance would remain active on the local level through legislative advocacy: "Both organizations will be advocating change and reform of the [historic preservation] process."