The spanking-new Bronx Library Center that will open a week from today looks decidedly out of context at the intersection of East Kingsbridge Road and Briggs Avenue, a stone’s throw from East Fordham Road. And that is not necessarily a bad thing.

It is not easy to define what that context is. Because it has long been one of the least affluent regions of New York, this area is full of three- and four-story houses that have not changed over the last 100 years and which are crammed at street level with every manner of mom-and-pop establishment. East Fordham Road meanders from west to east like London’s Kensington High Street or several other high streets in the sundry districts of that capital, but where it intersects Grand Concourse Avenue, suddenly you are in Lima, Peru. There is a seedy glory to this monster of a boulevard, a discordant collision of early-20th-century folies de grandeur and six subsequent decades of malign neglect. If you are feeling nostalgic for that vanished New York of the postwar years, or of the decrepit 1960s, or of a pre-Disneyfied Times Square, rest assured that it’s alive and well in this part of the Bronx.

Into this context, the new library has alighted like a flying saucer in a cornfield. Designed by Richard Dattner, it is clearly the most glamorous thing to happen to the neighborhood in years. I would guess there is nothing like it within a three-mile radius.

A five-story structure built along the ascending bias of Briggs Avenue, its bulk is a fairly orthodox Modernist affair, a pristine glass box. At street level and on the south side, it is accented with rust-colored stone cladding. The northern end, though similarly clad, rises as a turret whose summit consists of those ever-elegant brise-soleil striations that are so much in fashion these days. They are the best thing not only here but in the new Bloomberg Tower on Lexington Avenue and 59th Street, and in Philip Johnson’s recent Metropolitan, a residential tower on Third Avenue and 90th Street.

From one end of the building to the other is a looping, sharply angled roof that rises above a slightly recessed top floor and reveals, I believe, Mr. Dattner’s long-standing in volvement with the design of infrastructure. It recalls anything but the typology of a public library: Pioneered by Pier Luigi Nervi in Rome’s Termini train station, this roof design has been revived in SOM’s recently completed Terminal One at John F. Kennedy International Air port and in William Nicholas Boudova & Associates’s new West Midtown Ferry Terminal.

The slick, streamlined horizontality of the Bronx Library is emphasized further at ground level by a raking canopy whose granite-gray geometry has, like the rest of the building, impeccable High Modernist credentials. In fact, it is difficult to put your finger on any element of this building that would seem substantially out of place in the context of orthodox 1960s architectural practice. The composite, perhaps, is a little more varied than standard ’60s fare, and the manufacture of the parts, together with the use of materials, is far more sensitive than was true back then. But beyond that, there is little to orient us in the present architectural moment.

Though I was not able to gain a thorough sense of the interior, I can say that the Modernist logic of the exterior appears to be fully respected inside the building as well. Each floor consists of an expansive and undivided space articulated only by a few uninflected pylons that have been standard fare since Le Corbusier. Meanwhile, the main reception area consists of a dramatic green drum suspended from the ceiling in such a way as to channel the spirit of mid-century Modernists like Alvar Aalto.

Though Mr. Dattner is not one of the most widely known New York architects, he is surely one of the most prolific, especially as regards the many commissions he has received from the city. He cut his teeth as a young man back in the late ’60s with his Adventure Playground in Central Park. This was somewhat revolutionary at the time, since it was the first playground conceived as a unified recreational zone; its sandboxes, wooden mazes, and jazzy structures went far beyond older playgrounds, neutral spaces equipped with a slide, some swings, and a jungle gym.

More recently, Mr. Dattner has designed P.S. 234 in TriBeCa, with its curving, sawtooth footprint, as well as its elegantly gridded and contextual metal gates. Much more historicist is the northern entrance to the transit hub at Broadway and 72nd Street, which tries to imitate the turn-of-the-century southern entrance, which in turn imitates the vernacular vocabulary of Old Amsterdam. There is an element of ungainly pastiche in that building that is very different in spirit from the Modernist probity of Mr. Dattner’s latest effort in the Bronx.

Such willingness to adapt will not win Mr. Dattner the abiding respect of architectural purists, but at least it bears out the not dishonorable ideals articulated in his 1995 book, “Civil Architecture: The New Public Infrastructure”: “Those who design civil architecture labor at the intersection of their culture’s aspirations, political struggles and available resources. The realization of civil architecture requires civility, compromise, improvisation, accommodation, patience, tenacity and a sense of humor.”

At the new public library in the Bronx, these ideals have been admirably brought to fruition.