The architects at Erdy McHenry have produced some of Philadelphia's most imaginative and stylish new buildings, from the Schmidt's complex in Northern Liberties to the swirling dormitory tower on Drexel University's campus. They're increasingly in demand outside the city, too, and just completed a stunning modern dairy barn for Cornell University's veterinary school.

In short, they're not the kind of architects who need to scrounge for small-change commissions like the parking garage they just completed on Arch Street, across from the Convention Center. They say they took on the controversial assignment for the simple, if not exactly modest, reason that they felt they had the design chops to rescue a bad project. "We like a challenge," David McHenry, the firm's cofounder, told me.

His reasoning, unfortunately, reflects a common misconception that the only thing wrong with garages is the way they look. The internationally famous Swiss architects Herzog & de Meuron perpetuated the fallacy a couple of years ago with their boutique garage on Miami Beach's Lincoln Road, a dazzling trophy work that nevertheless occupies space that could be better used for other things.

But design will not save us from what's wrong with garages. The real problem with these utilitarian structures - and we're talking about the free-standing, aboveground kind, located in downtown settings - is that they distort how the city functions.

When you insert a garage on a dense, pedestrian-friendly block, you can't help but dilute the mix by widening the distance between people and their destinations. Meanwhile, new parking encourages people to drive instead of taking transit, which only further increases the demand for more parking. Putting garages underground, below mixed-use buildings, is expensive, but at least it minimizes the harm.

So, given the profound impact of aboveground garages on cities, it would be wrong to evaluate Erdy McHenry's design purely on looks. But given their swaggering promises, it would also be wrong to ignore the architectural results.

Erdy McHenry has clearly pulled out every design trick in their arsenal to overcome the natural limitations of the garage form, yet, in the end, their $27 million parking structure is as oppressive and lifeless as any other in Philadelphia.

With nearly all garages, the most unattractive features are the open parking decks and looming concrete walls. Erdy McHenry use their considerable design skill to camouflage those eyesores, but they fool nobody. A pleated scrim meant to hide the decks on Arch Street comes off as a cheap solution, like a bedsheet hanging in a window instead of curtains. That's still true at night, when LED lights turn the scrim the colors of the rainbow.

Perhaps the worst fail is the west facade, where a dark gray wall hovers menacingly over the picturesque, mid-19th century Arch Street United Methodist Church.

The architects attempt to break up the large expanse with an asymmetrical arrangement of fins, yet the wall still looks like a giant wave about to wash over the little church's peaked roof. An unfortunate elevator tower competes with the delicate Gothic steeple.

It wouldn't be an Erdy McHenry building if there weren't some nice stylish touches, such as the yellow band outlining the row of ground-floor retail spaces and an assertive "Park" sign. Its size and original typeface would do the sign-loving architect Robert Venturi proud.

Erdy McHenry also worked hard to make the garage environmentally friendly. The project boasts a green roof, electric car chargers, and windows that bring light into the garage lobby. But I doubt that any of these features will compensate for the energy expended by people driving into the city to park in its 540 spaces.

Still, the main responsibility for the garage's existence goes to the Nutter administration.

The project was first proposed in 2010 by developer Dennis Maloomian of Realen Properties as a way of attracting a hotel operator for an early 20th century skyscraper he owns at Broad and Arch Streets. The Convention Center had just been extended to Broad Street, eliminating several surface lots, and Maloomian argued that parking was in short supply in the area. The garage, he insisted, was also critical to clinching a hotel deal.

The problem was that his site wasn't zoned for a garage.

The Convention Center was purposely built without parking to discourage hordes of motorists from jamming the streets around the building, and to encourage visitors to use transit. The 1991 Center City Plan specifically prohibited parking next door on Arch Street in the belief that Philadelphia's downtown activity shouldn't be broken up by garages.

The Nutter administration has spent years talking up the value of lively, walkable streets.

But Maloomian only had to mention the word "hotel" to convince the city planning and zoning boards to bend the rules. Propelled by fears that his derelict tower, which sits like a prow at the entrance to the Convention Center, might remain empty for years, the garage sailed through the permitting process.

So, two years after Maloomian received his zoning variance, you would expect that his hotel project would be under way, right?

Not quite. Maloomian has yet to find an operator, although he insisted in an interview that he's close. Nor has he managed to sign any tenants for the garage's retail spaces.

So, let's get this straight: As of now, the Arch Street garage has brought no hotel, no new shops or restaurants, and no good design to the Convention Center's doorstep.

The only thing it has attracted to that dreary corner is plenty of motorists.