For the past month, traffic heading down Pennsylvania Avenue has had more than the Capitol Dome to distract its attention.

But the grid-like fluorescent green light emanating from a window in the National Gallery of Art’s East Building couldn’t be more distinct from the ornate neoclassical grandeur, which looms in the distance.

The installation, part of a Dan Flavin retrospective opening Sunday, which spans 35 years of the late Minimalist light artist’s work, is no doubt meant to attract attention. It’s the “only exhibit no one will ever have trouble finding,” quipped Earl Powell III, the gallery’s director.

It’s also likely to be one of the few exhibits at the gallery where one would be advised to bring along protective eye gear (as one sage security attendant could be seen sporting at this week’s preview). Indeed, Flavin’s manipulation of his light palette can be both mind-bending and, at times, eye-straining.

Before Flavin burst onto the 1960s art scene with his striking configurations of fluorescent light, he experimented with Abstract Expressionism. His initial forays into electric light were hybrids, a mix of the traditional (wood and paint) and the innovative (light). Accordingly, the first room of the exhibit strikes an anomalous chord with a grouping of his “icons.” These boxy, monochromatic wall installations are adorned with short strips of fluorescent tubes or lightbulbs, some flashing, all as kitschy as any futuristic bauble from a William Shatner-era “Star Trek” set. Flavin, a former altar boy, dubbed these secular takes on the sacred art form “blank magic.” Unlike their religious brethren, Flavin said, these icons were “dumb — anonymous and inglorious … constituted concentrations celebrating barren rooms.”

The effect of his light works on those rooms would be glorious, however.

In 1963, Flavin placed a single tube of fluorescent yellow light against a wall at a 45 degree angle, declared it his “diagonal of personal ecstasy,” and from there on out devoted himself to the medium.

His tools were simple: mainly straight fixtures (2, 4, 6 and 8 feet long) in which he placed a limited spectrum of 10 fluorescent tubes of color (four of these were white) purchased at hardware stores.

The possibilities of such an approach were endless. Flavin constructed his series of “monuments” (begun in 1964 and completed in 1990) to the Russian Constructivist Vladimir Tatlin — famous for his unrealized dream of building a 1,300-foot-tall Monument to the Third International — from just seven tubes of white light (three pairs of the same length, one different) arranged in varying groupings, angles and permutations. Eight of these “monuments,” each with a shelf-life of 2,100 hours or about 88 days and producing effects ranging from a New York City skyline to a shock of lightning, are included here.

The simplicity of Flavin’s spare, geometric light forms (more than 40 are on display at the National Gallery) belies their complex and varied intellectual underpinnings. Catholicism, James Joyce, a passage from Ralph Ellison’s “Invisible Man,” the principle of Ockham’s razor, and abstract expressionists like Barnett Newman and Jackson Pollock all played some role in the development of this radically different oeuvre.

Critics have frequently compared Flavin’s fluorescent tubes to French Dadaist Marcel Duchamp’s readymades. They are, after all, found objects — in themselves just another sterile product of the industrial age.

But Flavin’s best pieces do more than just declare fluorescent light to be high art. Unlike Duchamp’s porcelain toilets, the tubes of light could be manipulated to create new colors and visual dimensions. Two pieces in the exhibit, essentially frames of light set into the corners of rooms, tempt the viewer, much like Alice’s looking glass, with the promise of new worlds on the other side. A square of yellow, pink, and daylight fluorescent light dissolves into a peach shade on the space beyond. In another, yellow, blue and red commingle to produce a two-tiered visual effect, with the bottom square framing a purple dimension, above which hovers a rectangle of violet. (In the latter instance, the light also bathes the white walls of the gallery in that same brilliant violet.)

Other pieces are more intrusive. Rounding a corner, the viewer is accosted by a Vietnam War-invoking bow and arrow-like construction of red fluorescence — ominously dubbed “monument 4 those who have been killed in ambush” — jutting forth from a wall. In another room, the light sculpture colonizes the space with a geometric jungle of “greens crossing greens,” the literal title of two intersecting fences of light. Flavin humorously dedicated this piece to “piet mondrian who lacked green,” an allusion to the color’s absence in the Dutch modernist’s palette. (Flavin’s dedications are legendary, and several pieces in the show bear the name of a favorite contemporary, friend or artistic predecessor.)

Just as easily, however, Flavin’s works blend with the environment, as is the case in an untitled work featuring a line of white light running along the edges of the floor and ceiling of a corridor. His pieces, then, also serve as architectural accouterments, seamlessly illuminating and altering the pre-existing form. It’s hardly surprising then that Flavin’s light works have been used to accentuate everything from Frank Lloyd Wright’s Guggenheim Museum in New York to a Catholic chapel in Milan to an ex-army barracks in Texas.

Flavin, “an ardent Democrat” who enjoyed designing “really acerbic bumper stickers” to pass out during elections, according to his studio manager Steve Morse, clearly found inspiration in the political. A wall of warm white fluorescent-lighted discs in the shape of a right triangle is dedicated to the 1972 Democratic presidential candidate, then-Sen. George McGovern (S.D.), whose candidacy Flavin supported. A lithograph and silkscreen poster Flavin created for the “Art for McGovern” campaign is also included in the show.

The exhibit concludes with a room of sketches, graph paper on which Flavin has mapped out the blueprints of his works, and even a few examples of his early dabblings in Pop Art — a tomato can topped with an Aerolux lighted Virgin Mary, a mounted newspaper headline screaming the news of Marilyn Monroe’s death. In that same room is also a sheet of aged, unlined paper, adorned by a rough column of words written by Flavin in 1961 to sum up his thoughts on his incipient art form. Even then, it seems, Flavin was conscious of the exquisite ephemera of his creations.

“Fluorescent poles shimmer shiver flick out dim monuments of on and off art,” he wrote.

Pure, perfect, beacons of magic.

“Dan Flavin: A Retrospective” runs from Oct. 3 to Jan. 9, 2005 at the National Gallery of Art’s East Building. A two-day Flavin symposium, open to the public, will be held on Oct. 23 from 11 a.m. to 5 p.m. and on Oct. 24 from 2 p.m. to 4 p.m. in the East Building auditorium. For more information about activities related to the exhibit, go to www.nga.gov.