Others weren't so thrilled.
"Very, very disheartening," said Lower Providence township manager Joseph Dunbar, whose staff worked countless hours during the last three years to bring ARC into being.
Dunbar estimated the township would miss out on up to $1 million a year in tax revenue connected to ARC.
"We did everything we could possibly do to keep the project alive," he said. "Ultimately, they made a business decision to move outside Montgomery County. . . . It's a tremendous loss, and I don't think we'll realize what opportunity we had until this Revolution Center is open and moving forward in Philadelphia."
It's unclear whether the museum will be placed in the existing building, called the Independence Living History Center, or if the center will be demolished and replaced. Either way presents serious challenges.
The center needs repairs, including patches to a leaky roof. More complicated, at the center's rear stands a fairly new, multimillion-dollar air-conditioning system that cools buildings in Independence Park. That system has enabled park officials to remove weighty air-conditioning boxes from roofs, helping to preserve buildings by eliminating vibration and stress.
Whatever happens to the Living History Center, the air-conditioning equipment must remain, park spokesman Phil Sheridan said.
The reaction to ARC's move?
"My first thought when I heard it was, 'The British are coming! The British are coming!' " joked Meryl Levitz, president and chief executive officer of the Greater Philadelphia Tourism Marketing Corp. "If the resolution to the controversy is to move it to Independence Hall, I guess we have to say, 'Huzzah,' in the vernacular of the day. . . . I think it'll be a big draw."
The key point of the relocation plan announced by ARC executives and U.S. Interior Secretary Ken Salazar is a land swap. ARC agreed to exchange its 78 acres inside Valley Forge National Park for the property at Third and Chestnut Streets.
The two-story, red-brick Living History Center is an archaeological hub, with three full-time archaeologists and 35 volunteers sifting shards of glass, pottery, and other objects found in digs throughout Old City. About 300 visitors go to the center each day to watch archaeologists work, read about historic Philadelphia, or buy tickets for tours.
ARC's property consists of pristine woods on the north side of the Schuylkill, a pocket of land virtually surrounded by the national park. Historians say that the commissary for the Continental Army's 1777-78 winter encampment was there - though some experts dispute that - and that the area served as staging grounds for the army's departure.
Officials said it would take a year to complete the land exchange because of the need for title searches, surveys, and appraisals. If one property turns out to be more valuable than the other, the holder of the more expensive land will pay the other the difference in price, officials said.
The swap would end a nasty battle that has gone on longer than the Revolutionary War itself.
After contentious hearings before the Lower Providence Board of Supervisors and grueling, often volatile proceedings before the township zoning board, ARC received permission to build a three-story museum, a four-story conference center, and a trailhead structure on private land inside Valley Forge National Park.
But legal challenges from the National Parks Conservation Association, an advocacy group, promised to tie up the development for at least another year - and to strangle ARC's ability to raise money.
That threat remained even after ARC won an important early court ruling, when a U.S. district judge dismissed the NPCA's federal lawsuit. That decision is being appealed.
H.F. "Gerry" Lenfest, the philanthropist who leads ARC's governing board, had said he would consider any compromise solution - except changing the site. Yesterday, he credited Salazar, Mayor Nutter, and Gov. Rendell with shepherding the move to Center City.
"I don't know why we didn't think about it in the first place, except we didn't know anything was available," Lenfest said. "This is a breakthrough, and we're all enthusiastic about it. It's a better location for the American Revolution Center."
And a smaller one - which will result in a smaller museum, Lenfest said.
ARC already had placed a moratorium on construction of its planned "scholars' dormitory," which opponents criticized as a commercial 99-room hotel, and will drop that part of the plan, Lenfest said. It also will drop plans for parking.
ARC will consist of a museum and education center, size to be determined, he said. For the next year, ARC will undertake a fund-raising campaign - the dollar goal unknown at present.
In the suburbs, news of ARC's departure caused not only sadness but anger.
"I hope that the opponents and naysayers enjoy their hollow, destructive victory," said Albert Paschall, chief executive officer of the Montgomery County Chamber of Commerce. "Montgomery County has lost what would have been an international showcase."
ARC executives long had described the complex as a proud addition to Valley Forge, a museum to tell the story of the Revolution at the site of the Continental Army's soul-searing winter encampment. But opponents, including the NPCA and National Park Service officials, said ARC would harm wetlands, wildlife, and historic ground. They saw it as a desecration.
They supported building a museum on the south side of the Schuylkill, near the park visitor center.
Joy Oakes, senior director of the NPCA's Mid-Atlantic office, called ARC's move to Philadelphia "a very reasonable and good thing to do."
"It allows the museum to take a big step forward, and we support that," she said.
ARC intends to explain the Revolution through artifacts and manuscripts, lectures and symposia. At Independence National Park, it will join revolutionary sites including the Liberty Bell Center, the National Constitution Center, and Independence Hall.
"I think this is the absolute perfect place," said Cole, who took over as ARC president in January. "You've got the Declaration of Independence and the Constitution - what's missing down there? The full story of the Revolution."
Cole said he didn't want to discuss the impact of the NPCA's lawsuits on the decision to move because "today is a day to look forward."
But people familiar with his thinking said that after a thorough review of the project, Cole concluded that if the American Revolution Center was going to get built, it would have to move. There were too many legal and political obstacles at Valley Forge.
"It's a good day for our residents," said Richard Brown, a Lower Providence supervisor who ardently opposed ARC. "We can stop bleeding legal fees and get back to the business of improving the township. I'm relieved, and I'm happy this is happening on the Fourth of July. What an appropriate day to celebrate."
Contact staff writer Jeff Gammage at 215-854-2415 or firstname.lastname@example.org.
Contributing to this article were Inquirer staff writers Stephan Salisbury, Zoe Tillman, and Marcia Gelbart.