But they stress that the title has tangible benefits, too, with the potential to draw hundreds of millions of dollars in tourism revenue, strengthen Philadelphia's international image, and open business connections with the 266 other World Heritage cities around the globe.
"We have an opportunity to really look over the menu and decide what kind of relationship we'd like to foster," said John F. Smith III, chair of the Global Philadelphia Association, which worked on the bid. "We would like nothing better than to connect people, to achieve commercial marriages, to let people start talking directly to each other ... and see where it goes."
World Heritage cities have all made notable impacts on the world and are home to a UNESCO World Heritage site. Independence Hall became a UNESCO heritage site in 1979, significant because both the Declaration of Independence and the Constitution - documents that have had a profound impact on lawmakers around the world - were signed there.
Philadelphia became an observing member of the Organization of World Heritage Cities in 2013 and officials here have been campaigning for full status since.
Nutter on Friday called the designation "the start of a new and exciting chapter" in the city's history.
"As we celebrate this milestone, the next step is to focus on the future and how we can optimize this World Heritage City recognition to attract more people to visit, invest, work, study, and live in Philadelphia," he said in a statement.
Increased tourism revenue is the most apparent benefit. According to a study commissioned by Global Philadelphia, the designation - if properly marketed - has the potential to increase foreign visitation by 10 percent to 15 percent, about 60,000 to 100,000 people annually. That would generate about $150 million per year in expanded economic activity, according to the report.
Domestic tourism, the study estimated, could increase by 1 percent to 2 percent, generating an additional $100 to $200 million in economic impact.
City officials say the benefits go beyond tourism.
Alan Greenberger, the city's deputy mayor for economic development, said the goal is to build bonds with selected World Heritage cities similar to those that exist with Philadelphia's sister cities. That could result in university exchanges, shared research, or business-to-business partnerships, he said.
"In a very competitive global world, with so much information and so many possibilities at your doorstep, you start to say, 'I can't deal with all of that,' " Greenberger said. "So, who do we know? Who do we trust? Who do we have a relationship with?"
Denis Ricard, secretary-general of the Organization of World Heritage Cities, added that Philadelphia will gain access to programs that help cities maintain and promote their heritage.
"It opens up a full network of cities around the world," said Ricard, who toured Philadelphia in 2014 after the city petitioned for full membership.
Making the most of the designation will fall to the administration of Mayor-elect Jim Kenney. Lauren Hitt, Kenney's spokeswoman, said he had been briefed on the effort and expressed his support.
"Between the pope's visit, the DNC [Democratic convention], and now this new international honor, Philadelphia is clearly making great strides," Kenney said in a statement. "My mission as mayor will be to ensure that all our neighborhoods are included in this progress."
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