The convention of looking at paintings on museum walls is by now thoroughly ingrained. We walk into a room, survey its contents, and advance upon one or another of the pictures there to be surprised, delighted, informed, provoked or otherwise stimulated by an artist's vision of the world, in its framed rectangle. It's an old, pleasurable habit. The possibilities are practically limitless.

David Ireland, a San Francisco artist given to seeing things in a very different way, was invited some time ago to install a site-specific art piece at the Hirshhorn Museum as part of its ongoing series of "Works" exhibitions. After several visits to the cylindrical building, Ireland decided to transform the Abram Lerner gallery there -- the one with the huge horizontal window offering a panoramic view of the Mall. His intention was to upset the old convention, or at least to give it an edgy twist, with results that went on view Wednesday.

In a way it is a shame to tell the tale, for one would do better to stumble upon the Ireland piece unaware. But there's no getting around the telling. What Ireland did, with the help of Ed Schiesser and his exhibits staff, was block the existing window floor to ceiling with a new white wall like others in the museum, and cut five square openings in the new wall, each simply framed in white like an abstract painting, each focusing via an eccentrically shaped funnel upon a different segment of the panorama outdoors.

Presto: Expectations are confounded. These are, literally, Renaissance "windows on the world," and the art they reveal is life itself. It is quite a jolt to be lured to one of these "pictures" and to be content with a static, pretty scene -- the pedimented entrance to the National Archives building, say, or the tower of the Old Post Office -- when suddenly a yellow bus traverses the view, or a blue-sweatered jogger. Or to find oneself analyzing, just as if it were a painting, the compositional niceties and expressive implications of a view of Matisse's famous bronze backs in the sculpture garden, each back pierced cleanly at its small by a narrow pipelike railing on the balcony outside.

The most surprising view is done by mirror -- through one of the north-facing apertures you find yourself looking due west, at a postcard view of the towers of the Arts and Industries Building, the Smithsonian Castle and the Washington Monument. But not completely: The mirror does not altogether fill the opening, so you also get a partial view of the north side of the Mall. It's rather as if Ireland were playing the role of the Wizard of Oz and, at the same time, that of Toto, pulling back the curtain on his wizardry.

The piece, in other words, makes a viewer feel quite self-conscious: You're constantly catching yourself in the act of looking at "art." The feeling is refreshing, up to a point. It's good, insidious fun to be brought up short from time to time, to be forced to question what it is, precisely, that you're doing. And it can intensify perceptions. When that bus rolled by I experienced a tremendous rush. An ordinary bus, of course, but it seemed preternaturally yellow, touched by a magical light.

Ireland is a master at altering spaces -- probably his best work, and certainly his best known, is the house he's inhabited for 14 years in San Francisco's Mission District, which he has subjected to a sort of constant archaeological treatment, revealing in carefully adjusted fragments its past lives, secrets, mysteries. With Robert Wilhite, he six years ago created a strangely beautiful green room called the Jade Garden for visiting artists at the Washington Project for the Arts. (Naturally, he stayed there while the Hirshhorn piece was under construction.) His sizable artistic strengths are his quirky, original mind, his feeling for color and light, and his ability to transform ordinary surroundings and materials.

The Hirshhorn piece is part commentary, part exhortation. At its best, it sends you back into the museum with fresh eyes and a renewed respect for the seriousness of the engagement between viewer and art object. At the same time, it presses you to understand that such encounters are circumstantial and must be reaffirmed in the real world, out there.

But the piece suffers, too, from its primer-like insistence. If the questions it raises are appropriate to the setting, you still find yourself becoming impatient after a while, wondering, "So what's next?" The problem is perhaps due to the fact that the concept is more interesting than the setting; it's insufficiently transformed. The separate elements in it do not add up to a moving, cohesive whole. The best view of the room is from an oblique angle -- the framed openings, covered with a delicate white scrim, emit an otherworldly glow, promising some sort of revelation. Yet it is a promise only partially kept.

Ireland, incidentally, had another striking idea for his "Works" project: Envisioning the cylinder as a birthday cake, or as an ancient artifact of untold ritualistic function, he proposed to ignite a ring of fire at the edges of its roof. Spectacular. Edgy. Surreal. Appropriate to the celebratory purposes of the Mall but lacking conventional decorum. Unfortunately but understandably, what with the congressional art police in full preen these days, the museum said no to the idea.

Organized by chief curator Ned Rifkin, the Ireland installation is the 10th in the series of "Works" exhibitions. It will remain on view through Nov. 4.