Whatever you might think of Christian de Portzamparc’s LVMH headquarters at 19 E.57th Street,it may well prove to be the most influential New York building of the past decade.

For my part, I find it a somewhat overrated pile. Not enough spark or energy marks the interaction of its pale surface plates, and the ungainly crevices created by that interaction seemed from the outset, seven years ago, to invite the accumulations of soot that have since materialized. Nonetheless, a number of buildings springing up around the city have clearly taken what they needed from this prime example of Deconstuctivist architecture.

Though Mr. Portzamparc did not invent the faceted facade, his building has been more influential than any other of its kind.You find traces of it in the weirdest places: in the towers of the Time Warner Center, in Daniel Libeskind’s original design for the Freedom Tower, and in the Bank of America Headquarters at Sixth Avenue and 42nd Street, designed by Cook + Fox and scheduled for completion in 2008. But the debt to Mr. Portzamparc’s building is far more evi dent in two other soon-to-be-completed Manhattan towers.

The first of these is the office building Kohn Pedersen Fox designed for 505 Fifth Avenue, at the northeast corner of 42nd Street, overlooking the library. I wrote about this building several months ago and was somewhat disappointed at that time. I am happy to report, however, that the finished product is far better than I foresaw back then.

In building after building, KPF has proved itself to be among the most reliably elegant architectural firms in the city. It can be counted on to show a re fined visual intelligence that banishes any sense of cutting costs or corners, and that is the case at 505 Fifth Avenue. A dark-hued, 30-story tower on a base, it positively sparkles.The faceted mass resolves itself harmoniously by the time it reaches the foursquare, rightangled serenity of its lantern. You could argue that this rappel a l’ordre is a subversion of the subversion inherent in Mr. Portzamparc’s original, as well as in the Deconstructivist style in general. But isn’t that how the avant-garde always evolves when it is embraced by the mainstream?

The lobby, by the way, represents one of the more oddly grandiose new entranceways in Manhattan. Through a perspectival trick, the eloquent emptiness of this granite-faced interior seems to narrow as you progress into the building, as though it were intent on bearing down upon the frail and solitary human being who occupies the reception desk. The visitor, too, feels belittled by this omnivorous maw of an entranceway, and the oddity of it is that one enjoys the process of belittlement, which is not without a sense of humor. The grace notes of the design are less structural than they are the result of lighting: All sorts of interesting mood effects are evoked by the choice deployment of soft, phosphorescent accents of green and lavender light.

In order to understand the success of this building, it suffices to compare it with Ismael Leyva’s 57 Place, a 36-story residential tower on 57th Street right off the northeast corner of Third Avenue. It is a sign of the times that although this building rises over a largely commercial district and looks for all the world like an office tower, it has been sacrificed, like so much else in Manhattan, to the ever-hungry market for residential real estate. As such, it comprises 71 “high-end” units, according to the architect’s Web site.

The site further informs us that “the building is designed as a pure geometry of glass surfaces.” Its “dynamic combination of minimalist shapes” is meant to take advantage of the lower height of the adjacent building at the corner of Third Avenue. The result, we are told, “is a daring composition, generating a volume with diamond-like facets.”

The reality is somewhat less than that. Set this tower beside 505 Fifth Avenue, and you will understand at once the difference between real, tough architectural thinking and merely derivative construction. There is little evidence here of the care and quality that are so conspicuous in the design and execution of 505 Fifth Avenue. Instead of sheer, luminous glass, you have a clumsy fretwork of mullions that extends across the entire facade, imparting a sense of fatigue, dowdiness, and cost-cutting to the entire project.

In the KPF building, there is an effortless authority and an easy grace to the way its various parts fit together and resolve themselves like a wellmade Cubist collage. Though 57 Place, by contrast, is a simpler building, it attests to a sudden loss of attention and energy, as the once-radical Deconstructivist idiom collapses into dreary standardization.

jgardner@nysun.com