In Manhattan, where big new buildings are constantly sprouting up everywhere, it would seem a little odd for someone other than the owner or the architect to express pride in, say, the Time-Warner Building or the new Morgan Library complex. But in most other places in the world, such pride is often attested by the citizens, and it makes perfect sense. And for the residents of the Bronx, which is only now emerging from an architectural slumber of nearly fifty years, it is easy to see how the Bronx Museum of the Arts, when it opens on Saturday in a much enlarged version, will provide a sense of elevation, a sense that things are looking up in the borough.

It is a fair guess that, sooner or later, people will start referring to this new three-story structure as the Accordion Building. It unfurls along the Grand Concourse like the folds of that estimable instrument in a stunning mirage of shimmering aluminum. A little jagged and a little syncopated, the building suggests the lively, off-kilter rhythms associated with the Latino culture that now predominates in the borough.

Arquitectonica, the Miami-based architectural firm that conceived the building, blatantly strove to come up with some iconic form, and it succeeded. To be blunt about it, iconic buildings tend to look ugly and stupid, and their main selling point is that, even if they look ugly and stupid, they at least are not the usual fare. Sometimes, however, as here, they achieve what they set out to do: to create a landmark that is fun to inhabit and that clamorously asserts the forward-looking virtues of the entity that paid for it.

At the same time, Arquitectonica has succeeded in contextualizing the building within the seemingly endless continuum of the Grand Concourse. Beginning at 207th Street, this avenue progresses in a catenary of mostly six-story residential structures down to 138th Street, where the Madison Avenue Bridge leads into Manhattan. Nowadays, of course, most architects claim to respect context, but they usually don’t. The architects of the new Bronx Museum, though, have fulfilled their claims.

Like much of the Grand Concourse, the building’s most defining architectural style is Art Moderne, an idiom from around 1930 that stood somewhere between art deco and modernism, purging itself of the Gothic decorativeness of the former without yielding to the severity of the latter. This idiom is especially evident in the insistently horizontal canopy that stretches across the length of the façade, articulating the museum’s name in fine metallic letters that recall those of Radio City Musical Hall. Meanwhile, on either side of the main façade, cinderblock walls have been enlivened with intricate black and white patterns intended to evoke Bronx row houses.

The interior, however, is spare to the point of minimalism.As you pass through the irregularly spaced double-height lobby into the galleries, you notice bare concrete floors that are doubtless intended to invoke the borough’s rugged populism, as well as the dour functionalism that the Chelsea art world currently favors. Nevertheless, the floors’ lack of finish feels like being a hair’s breadth away from not being finished at all. The second floor, articulated by rounded white columns, succeeds better, and serves as an kind of auditorium and screening room, with a terrace to the east and, to the west, the interior of the accordion façade, illuminated by tall, fritted windows that are almost invisible from the street. The third floor has been given over to an education center.

The Bronx Museum will look even better with the completion of its next stage of expansion, still some years away. Having acquired three adjacent lots, the museum intends to build at its southern end a residential tower, whose base will replace a far inferior structure, a glass-andsteel cage that began life as a synagogue in 1961 and was expanded in 1988 by the firm of Castro-Blanco, Piscioneri & Feder.

Ten years ago, few could have imagined that the Bronx’s fortunes could progress so far that a fashionable condominium tower would rise above a restored Bronx Museum of the Arts. In fact, the museum occupies a part of the borough that is of genuine urban interest, and that deserves more attention than it usually receives. The museum sits across the street from the lovely Joyce Kilmer park, and like the august municipal buildings on its southern end, the park embodies the City Beautiful dreams of Louis Aloys Risse, the Alsatian immigrant who designed the Concourse more than a hundred years ago. Until recently, this part of the city could boast only one important piece of contemporary architecture, Rafael Vinoly’s imposingly brutalist court building at 166th Street.With the opening of the new Bronx Museum of the Arts, it now has two.