On an unusually warm and lustrous January day last week, I thought it would be fun to return to the Bronx, whose new library on Briggs Avenue I wrote about in a recent column. Heading into the sun, I descended Grand Concourse Avenue on foot all the way to where Madison Avenue Bridge spans the Harlem River, leading you into Manhattan at 138th Street.

The Grand Concourse is odd as avenues go. It does not bear out the vitality that it promises at its northern end, near East Fordham Road. For most of its length, it is a vast, gray, treeless expanse whose pre-war buildings never coalesce into a coherent aesthetic. It betrays some spark of early 20th-century City Beautiful planning around Joyce Kilmer Park before plunging into the 1970s gunk of Hostos Community College and a perilous tangle of infrastructure just outside the gates of Manhattan.

Nevertheless, two structures stand out: the Bronx Housing Court and the ongoing expansion annex of the Bronx Museum of the Arts.

The first building, completed in 1997, is one of the most effective works of Rafael Vinoly, a native of Argentina. In a city with all too few iconic structures, this one comes as a pleasant surprise, especially since it inhabits a part of the city that, I would guess, design types do not often visit.

Rising nine stories, the courthouse stands in striking contrast to the Art Deco and Art Moderne vocabulary of most buildings on Grand Concourse Avenue. It is not a machine for living, a la Corbusier, but rather a purely ornamental tribute to that functionalism. Nor for that matter does it look especially like a courthouse. Its hulking facade is covered in sandstone and Roman brick that alternate in a series of horizontal bands over a concrete matrix. At various points – along the base, at the summit, in a vertical strip on the left – the blockish structure is punctuated by glass and aluminum curtain walls, whose emphatic grids recall the pure geometry of Sol Le-Witt’s early work.

What is most striking about the exterior are the bold, volumetric recessions of the facade, the way, for example, the entrance recedes from the street line even as its cantilevered canopy shoots out beyond it. Especially elegant is the way the bulkiness of the whole is challenged by three needle-sharp flagpoles to the left of the entrance.

Only a few blocks south you will find the Bronx Museum of the Arts at the northeast corner of 165th Street. This institution, which began life in the lobby of the Bronx County Building, eventually took over a postwar synagogue designed by Simon Zelnick in 1961. By 1988, it expanded into the squat and darksome glass-and-steel edifice you see today, by Castro-Blanco, Piscioneri & Feder.

Rising up just to the north of that structure, a strange and jaunty building is being born. It recalls, perhaps inadvertently, a bandoneon, or Argentine accordian. This is the work of Arquitectonica, a Miami-based firm with a strong Latin flavor to its creations. Given the largely Latino cast of this part of the city, it is perhaps no accident that the present project, like the previous expansion and the Housing Court, was designed by architects with strong Latin American connections.

Arquitectonica is one of the more visible, “edgy” new firms on the stage of world architecture. If nothing else, it speaks well for the New York City Department of Design and Construction that it had the enterprise to engage Arquitectonica for this expansion.

Until now, the firm’s presence in New York has been hardly illustrious. It was responsible for the truly atrocious Westin Hotel at 42nd Street and Eighth Avenue, with its coated windows of irregularly colored glass and a crass arc of light that, in the evening, swoops up and down the entire southern expanse of the building. Such failure was especially regrettable given that the work Arquitectonica has done outside of New York, especially in Miami, has been far, far better. The firm’s signature is a kind of jazzy, ethnic take on Modernism, with a trace of winsome deconstruction thrown in, that recalls the pulse and tone of southern Florida.

Fortunately, that quality is borne out in the Bronx Museum. Even in its partial state of completion, the three-story structure of the building has assumed something very close to its finished form, a series of shifting and irregular planes that float from north to south along the avenue. The three other faces of the building, besides the signature facade on Grand Concourse Avenue, will be covered in metal and concrete block masonry whose varied patterns are intended to suggest the brick patterns of the neighborhood’s Art Moderne heritage. According to the rendering, these are enlivened on the sides by a sequence of razor-thin strip windows and a perforated wall at the base. The cantilevered canopy, which recalls that of the new library three miles north, not only has Modernist credentials, but recalls the Art Deco spirit of many buildings in this part of the city.

The $15 million addition to the present 34,000-square-foot museum will expand its gallery and exhibit space while providing classrooms, a sculpture court, administrative offices, and a restaurant. It is scheduled to open to the public in the spring of 2007.

jgardner@nysun.com