Philadelphia was admitted into a very exclusive club this month, the Organization of World Heritage Cities, and it has been basking in the glow ever since. But being a World Heritage City should not be confused with being a city concerned about its heritage.

The last few years have been disastrous for Philadelphia's architectural patrimony. Grand stone churches are falling like autumn leaves. This week, it was a stately sanctuary on 12th Street where the barrier-busting singer Marian Anderson gave her first performances. The city's stock of notable buildings is being steadily eroded by neglect, indifference, and, especially, the housing boom, with its insatiable appetite for buildable lots.

The Nutter administration hasn't exactly gone out of its way to stabilize the situation. During the last eight years, a paltry 64 properties were added to the city's historic register. Not that the protected ones have fared so well. We've just lost two landmarked theaters, the Boyd and the Royal, to developers who were able to exploit the Historical Commission's financial-hardship exemption.

That loophole has become a favorite tactic for developers who just happen to find themselves with historic buildings that require costly repairs. Even as city officials celebrated the public-relations coup of the World Heritage designation, another developer was filing for hardship.

This time, the target isn't a cultural extrovert like the Boyd, but three lesser-known structures that provide the backdrop to our daily travels through the Rittenhouse Square neighborhood: an exuberantly decorated coffee shop, an early apartment house, and a funeral home. The trio - on Sansom Street across from what used to be the Boyd auditorium - sit at the edge of an acre-size empty lot owned by Southern Land Co., which plans a mixed-use development fronting Rittenhouse Square.

Southern Land's application, which is as thick as a concrete block, probably won't be reviewed by the Historical Commission until February, when it will be the problem of the new mayor, Jim Kenney. That promises to make the Southern Land case the first big test of his commitment to historic preservation.

Will the Kenney administration continue to treat historic buildings as an obstacle to development? Or will Kenney be the mayor who finally recognizes that our three-century collection of old buildings is an asset that enriches Philadelphia culturally, physically, and economically?

Kenney certainly said the right things about preservation during his campaign. As a councilman, he introduced a bill that would have protected more buildings by speeding up the pace of designations. He also spent 13 years in a marketing role at Vitetta, an architecture firm known for its preservation work.

But like Mayor Nutter and his predecessors, Kenney is also ardently pro-development. He owes his victory to the support of the trade unions, whose world revolves around constructing new stuff, not preserving the old.

Kenney's transition team could be an indication of his future leanings. When the members were first announced, there was no preservationist on the housing, planning, and development committee. According to Kenney's communications director, Lauren Hitt, that's because the name of Jim Straw, a preservation architect, was inadvertently left off the news release. Still, it's a rather homogenous bunch, dominated by affordable-housing advocates. Though that subject clearly deserves more attention, it's disappointing that the committee doesn't also include an architect or quality-of-life advocate - the sorts of people who might be sympathetic to design and history.

But back to Sansom Street. The seven-story Warwick apartment house, built in 1903, and the Oliver Bair funeral home, from 1910, are protected because they're part of the Rittenhouse-Fitler historic district. But the coffee shop, which began life as an ordinary rowhouse in 1855, is considered significant because of the elaborate tile facade it received in the '20s. All are now in poor condition, according to the engineering report from Keast & Hood included in the hardship application.

They didn't get that way by accident.

The trio fell into near-ruin under the ownership of a public agency, the Philadelphia Parking Authority. The authority acquired the buildings in 1997 (when the Warwick still had tenants) and sat on them for a decade in the hope of building - wait for it - a parking garage on Rittenhouse Square. The Historical Commission became the authority's enabler when it approved the demolitions in "the public interest."

Fortunately, Common Pleas Court overturned the commission's action, saving the buildings and sparing Rittenhouse Square the indignity of a large garage on its doorstep.

That was 2007, just as the big recession was setting in. The properties sat vacant for eight more years, until the assemblage was acquired this year by Southern Land for $30 million.

Now the company says fixing the buildings would be a financial burden. Sound familiar? The Boyd's owner made the same argument after buying the theater. The Boyd hardship decision sent a clear message about the city's preference for development over preservation: Buy it, and you can demolish.

Southern Land's chief, Tim Downey, acknowledged in an interview that he never took time to check the condition before the purchase. Because the historic buildings aren't in the way of the tower Southern Land wants to build, he figured he would incorporate them into the project.

Once fixed up, they could have housed shops on the ground floor, apartments or offices above. That would have dovetailed perfectly with Pearl Properties' new design for the Boyd Tower. Designed by Cecil Baker + Partners, it does a terrific job of reestablishing activity on Sansom Street. The complex project includes a midrise apartment building on the north side of Sansom that will be lined with ground-floor retail.

Apart from the proposed demolitions, Southern Land's development has a lot to recommend it. Construction on the empty lot facing Rittenhouse Square is long overdue, and Downey has hired a credible architect, Chicago's Solomon, Cordwell, Buenz, which designed Market Street's Murano. Unlike the Parking Authority, he's smart enough to know that Rittenhouse Square deserves better than a garage. He plans condos, rental apartments, retail, and underground parking. Why not? It's a can't-lose location that promises big profit.

But to do all that, Downey is going to need a zoning change to exceed the site's height limit, as well as permission to close a portion of Moravian Street.

That's a lot of "asks." How about a "give"? If Southern Land doesn't want to spend its own money to renovate the historic buildings, how about giving them to Project HOME for affordable housing?

Southern Land would get the tax write-off. The city would preserve a pocket of affordability in an increasingly pricey neighborhood. Philadelphia's historic buildings would get the respect they deserve.

And then we might live up to our new status as a World Heritage City.