America is slouching toward recession, and suburban home builders are in a time-out, but in Philadelphia developers are still dreaming big dreams. Indeed, the size of those dreams keeps growing bigger.

In Society Hill and Spruce Hill, two neighborhoods renowned for their low-rise architectural cohesion, developers are aggressively seeking approvals for new projects that would seriously bust the local height limits. It's as if no one told these builders about the mortgage-lending crisis.

From a big-picture perspective, there's some comfort in their proposals. Developers wouldn't be talking about more tall buildings unless they felt confident that Philadelphia could weather the coming economic storm. The projects, which combine hotels with other uses, also suggest that the downtown construction boom of the last few years isn't a passing fad, but part of a deeper commitment to cities and urban life.

Try telling that to residents who have nurtured their enclaves through decades of hard times. They can't help but worry that the multistory arrivistes will destroy the very qualities that now make their neighborhoods desirable - cozy tree-lined streets, houses that wear time's patina, modest commercial buildings. If developers insist on intruding, they argue, why can't they just build more of the same?

The answer is as simple and complicated as the price of land. The decade-long building boom dramatically altered the city's construction paradigm. Downtown land, once cheap enough to squander on surface parking lots, is suddenly valuable, as evidenced by the recent sale of a Rittenhouse Square acre for $37 million. Such prices demand height and density for developers to recoup their costs.

So in a city built rowhouse by rowhouse, the tall building is becoming, by default, the new norm, not just in Center City but also in the ring of surrounding neighborhoods. As James Templeton, the architect for Society Hill's proposed Stamper Square, bluntly put it: "You're not going to see rowhouses built downtown in large numbers ever, ever again."

If that's the case, how does a city famed for its gentle, historic neighborhoods respond?

What the city desperately needs is a skyscraper policy. Ideally, it will take shape as the Zoning Reform Commission rewrites the zoning code. But those results are years away, and the high-rise proposals keep coming. The two latest flash-point projects, Stamper Square on the old NewMarket site and Campus Inn at 40th and Pine Streets, are an opportunity to start articulating a philosophy now.

Both projects involve hotels, public dining and, in the case of Stamper Square, high-end condos. It's no accident that the developers targeted neighborhoods just beyond the high-priced orbit of Center City. Their designs try to minimize their bigfoot proportions with refined architectural detailing and setbacks. But there's no hiding that they're really high-rise buildings in a low-rise world.

Stamper Square, the new design by H2L2 for Bridgman Development, is the latest in a series of tall buildings proposed for the ill-starred NewMarket site. This one comes closest to establishing precedents that Philadelphia can use in the future.

The architects have carefully arranged the building mass so that it respects the colonial-era houses on its borders. On the Second Street side, across from historic Headhouse Square, the proposed hotel keeps to the height of the adjacent townhouses. As the structure moves deeper into the block, it grows to six stories. The building doesn't straighten up to its full height of 15 stories until it's at Front Street, on the neighborhood's far edge.

Such a sympathetic massing provides a useful lesson for future skyscrapers. By splitting the tower into two asymmetrical shafts of 166 and 163 feet, the architects lighten what could have been a heavy slab wall on Front Street, while at the same time making a subtle reference to the trinity/townhouse mix that gives Philadelphia's streets their character. The towers overlook a big street, which means they don't try to crash an intact block or diminish Society Hill's authenticity. Because they're really a continuation of the developing Front Street high-rise corridor, they won't stand alone. Plus, the parking is underground.

The developers of Campus Inn - Campus Apartments, Hersha Hotels and Tom Lussenhop - also argue that their 11-story, 115-foot-tall hotel is an extension of a commercial corridor along 40th Street, between the major transit connections at Market Street and Baltimore Avenue.

It's true that there are tall buildings along the street, but they're clustered toward the north end. The street really shifts gears south of Spruce, when it becomes the island of Italianate mansions called Spruce Hill.

If many of those homes had not long ago been turned into low-rent, ill-kempt student housing (many operated by Campus Apartments), the area might rival New Orleans' Garden District. Unlike Society Hill, Spruce Hill didn't have the good political luck of being granted historic-district protection. The mansion that occupies the Pine Street corner has been trashed beyond recognition.

Because of its sorry state, the developers identified the high-visibility corner as a good choice for an extended-stay hotel, aimed at serving out-of-towners who visit the West Philadelphia hospitals for outpatient treatment. The developers planned to tear down the house and replace it with a five- to seven-story hotel. That mid-rise would have made a fine transition from the commerce of 40th Street.

Ironically, the ruined house is protected as an individual historic building, even though the Historical Commission acknowledges it would never qualify for that honor today. Yet, the commission nevertheless voted to block its demolition. So the developers switched tactics. They offered to restore the old house, in exchange for being allowed to erect an 11-story hotel in the backyard.

Like Stamper Square, this hotel design, by Atkin Olshin Schade Architects, tries its best to respond to its surroundings. If the site had been on the neighborhood's edge, say Baltimore Avenue, that strategy could have worked. But the ungainly slab will have to be squeezed between two Victorian houses, virtually flush with its neighbor's property line.

The bargain with the Historical Commission does more harm to the gracious neighborhood than demolishing the wrecked house would. This is not preservation; it's re-creation. Better to tear down the house, and allow a reasonably scaled replacement, than jam such a behemoth into the mix.

A soaring tower is a thrilling thing that imparts energy and relevancy to a modern city. But there is also undeniable pleasure in walking among blocks of gentle urban buildings that march together at the same height. Philadelphia is lucky to have both types of places. It just has to decide which one goes where.

Contact architecture critic Inga Saffron at 215-854-2213 or