First in a series about the national pavilions at the Venice Biennale.

There was once an empire whose might and influence gave it a worldwide reach. It didn't have much in the way of foreign territories, but it could project its force at will and had a culture and a commerce that did much of its projecting for it, anyway. And then it came up against a rival Muslim culture from the East, newly revived after hard times. Without even recognizing it, the great empire, serene in its self-confidence, first teetered, then slid into decline.

For years, its artists didn't seem to notice. They made works with as much panache as ever, even as the end began to loom. But underneath that facade, the best of them made elegiac art that read the writing on the wall.

That empire was Venice, facing a long decline after the Turks sacked Constantinople in 1453. But the newest works of veteran American painter Ed Ruscha hint that it might also be the United States -- today, tomorrow or maybe at some date a little further off.

Ruscha's latest project, boldly titled "Course of Empire," opened yesterday at the 51st Venice Biennale, the world's most important festival of contemporary art. At the invitation of curators Linda Norden, of Harvard's Fogg museum, and Donna De Salvo, who works at the Whitney Museum in New York, Ruscha agreed to be his country's representative. Ten big Ruscha canvases now fill the neoclassical American pavilion in the Biennale gardens, which stretch right across the tip of Venice.

Ruscha wasn't an obvious choice for the job. At 68, he's a grand old man of American painting, rather than the kind of bright young thing that other countries often send to Venice. With this project, however, Ruscha has achieved the Holy Grail of Biennale art: to make work about the place you come from and stand for, while also making work that speaks to where it's being shown.

Half of Ruscha's Biennale pictures have been around for more than a decade. In 1992, he painted some black-and-white pictures he called his "Blue Collar" series, showing icons of American industrial culture: a big, bold building with the words "Tool & Die" stenciled on its side; others marked "Tires," "Tech-Chem" and "Trade School." There was even the top edge of a phone booth, with "Telephone" across its front and rays of sun streaming from the clouds behind. The picture conjures up Superman's modern Metropolis, where the all-American Man of Steel could duck into one of those newfangled booths and come out in tights, and a blaze of glory.

By painting these imaginary scenes in black and white, Ruscha was tying them to times long gone. Even his techniques are borrowed from the past: Reflections in his buildings' windows are painted as commercial artists would have rendered glassware in an old-time catalogue. The words he puts onto his buildings' sides are rendered using sign-painters' vanishing skills, designed to stick a name onto an office door: In Ruscha's paintings, letterforms that ought to seem as though they fill a whole facade look instead like they might be two inches high. (Ruscha himself learned the techniques of commercial art in school in the 1950s; he's never abandoned them.) Like all nostalgia, these pictures have their share of sadness. You may be doing well right now, and have a past that's equally great, but as soon as you look back on it there's longing in your gaze.

For his Biennale project, Ruscha decided to bring this older series into the present by making five "responses" to its images.

The present of Ruscha's new works comes in color, but that doesn't mean it's cheerier than the grays that preceded it. A few weeks ago, speaking on the phone from his Los Angeles studio, Ruscha said that his latest pictures "air my doubts about progress in the world, and hopes for the world. . . . They reflect my feelings about how things change -- and that they don't always change for the better."

In the present, the trade school sign, once full of hope for the future, has been whitewashed. The school's windows are boarded up. It is surrounded by fencing and barbed wire that vandals have already cut. ("It's abandoned," Ruscha said, "or ready for the wrecking ball. And that in itself is a step in the evolutionary process.") The "Tech-Chem" building, site of invention and manufacture and good old American can-do know-how, has been replaced by "Fat Boy," some kind of generic big-box store. It is shown against an infernal, blood-red sky.

The old "Tool & Die" headquarters has traded its straight-ahead signage for something more global. It's now lettered in at least four Asian-looking scripts (all of which are his own invention, Ruscha said). It bears a corporate symbol that is somewhere between a yin-yang sign and the logo on a bottle of Pepsi. Along the bottom of the building's other side, disenchanted locals have responded with various graffiti, including a swastika.

The iconic phone booth is simply gone. It has fallen victim to the cell phone's rising tide. In its place is empty sky, framed by a tall concrete lamppost and a recently planted tree. Whereas the old phone booth ended where the sky began, and was meant to shelter stopped pedestrians.

Actually, that open sky between pole and tree isn't truly empty. It's full of a wan, gently golden light that overflows with melancholy.

It is the light that sits behind any of a dozen sleepy-sad Madonnas, painted in Venice by Giovanni Bellini in the years to either side of 1500. It is the light behind the nudes of Giorgione, Bellini's pupil, as they recline on grass in twilit lassitude. It is the light of a classical myth by Titian, another student from Bellini's studio, that renders a golden past that cannot be recovered. It is the light that Venetian painters used for the next few hundred years to render the imaginary scenes of crumbling greatness they called capriccios. These landscapes full of ruins often seem to show a view of the Venetian Empire that looks longingly backward from a future when things have at last collapsed.

(Even the light-rimmed clouds in Ruscha's black-and-whites look suspiciously Venetian. The rays of sun behind his phone booth could have come straight from Titian's great "Assumption of the Virgin." In Venice, even Christian triumph could have an element of sad nostalgia in it. After all, Renaissance artists rather liked the old, classical dispensation that theologians claimed had been replaced by Christ's new one.) Ruscha says he loves Venetian art and haunts the city's museums when he's in Venice.

He also says that a more immediate source for his new work is the famous series finished by American painter Thomas Cole in 1836, from which he stole his project's title. (And which Ruscha says he came across only after starting his Venice canvases.) Cole's series of paintings documents the birth, rise, flourishing and death of an imaginary realm, so just by borrowing its title Ruscha evokes a falling away from grace. But what makes that evocation take effect in the paintings themselves is the light that Ruscha -- and Cole, for that matter -- owes to the Venetian painters who worked after their empire had begun its slide.

Representing the U.S. at the Biennale, Ed Ruscha's "Course of Empire" series twins his "Blue Collar" paintings from 1992, top, with newer, grimmer versions.Ruscha's first "Tool & Die" has given way to a more globally corporate look.Ed Ruscha's early-'90s iconic telephone booth, top, contrasts sadly with his 2005 "Site of a Former Telephone Booth."Ed Ruscha in 2004. His Venice Biennale artworks "air my doubts about progress in the world."