ATLANTA — What, exactly, do you do with a 130-year-old work of art, mythmaking and Civil War history that is longer than a football field, more than 40 feet tall and urgently in need of a new home?

This city is finding out. After decades of deepening disrepair and disinterest in the painting commonly known as the Atlanta Cyclorama, workers this month are moving the panorama as part of a $35 million plan to rescue and maintain a titanic, deteriorating example of an art form that has mostly disappeared.

Saving “The Battle of Atlanta,” which is among the largest oil paintings in the world, has proved to be an undertaking of remarkable complexity. It is rife with logistical tests, engineering quandaries, curatorial challenges and political and racial sensitivities that linger more than 150 years after Gen. William T. Sherman’s military campaign here. Yet after taxpayers spent years supporting an imperiled painting in a building troubled by leaks and temperature fluctuations, formal opposition to the effort, which is privately funded by multiple philanthropists, is strikingly scarce.

“The fact that this painting has survived when so many others were left out to mold and rot and get burned up and whatever is nothing short of a miracle,” said Gordon L. Jones, the senior military historian and curator at the Atlanta History Center, which reached a license agreement with the City of Atlanta to display the cyclorama.

“Everything that we know about Civil War memory, all of those stories, can in some way be described by using this painting as an example,” Dr. Jones said.

Indeed. “The Battle of Atlanta,” prepared in Milwaukee by a team of German artists, was completed in 1886, when cycloramas — massive panoramic projects intended to give viewers the sensation of standing in the depicted landscape — were a leading form of entertainment, and the colossal works traveled the country. During its tour of the North, “Atlanta” was widely interpreted as depicting the 1864 struggle here for what it was: a decisive and pivotal victory for the Union that left an estimated 12,140 people dead, most of them Confederate troops.

Then the exhibition moved to the South, and in November 1892, The Atlanta Constitution newspaper printed a masterstroke of spin: an advertisement that said the cyclorama’s scene was the “only Confederate victory ever painted.” The painting swiftly attracted large, and almost exclusively white, audiences and was donated to the city around the turn of the century.

But the crowds dwindled, in part because motion pictures increasingly replaced cycloramas as entertainment, and generations of decline began. A major restoration that concluded in 1982 bought the Atlanta Cyclorama more time before the painting’s quality and appeal began to wane again. In recent years, elementary schoolteachers leading rite-of-passage field trips were among the most loyal visitors to the cyclorama.

“I remember that when I took my permission slip home, my mom and my dad had a conversation,” said Mayor Kasim Reed of Atlanta, 47, who is black. “I remember it not being a typical permission slip that was quickly signed.”

But it fell to Mr. Reed, who will leave office next year, to help solve the contemporary riddle of what to do with the cyclorama, which black residents, in an earlier time, were allowed to view only one day a month. The city announced the agreement with the Atlanta History Center in 2014. The center will display the 19th-century relic on its 33-acre campus, located in an upscale area of Atlanta that includes the Governor’s Mansion and some of the city’s finest restaurants.

The plan comes — somewhat serendipitously, its organizers said — at a time of scattered efforts in the South to move beyond the traditional Old South narrative surrounding the Civil War. In 2014, for example, the Georgia Historical Society dedicated a marker that sought to undermine what it described as “popular myth” about Sherman’s cruelty during the war.

“It helps to bring some emphasis to why what happened here was important and why it’s not your grandfather’s Civil War anymore,” Dr. Jones said of present-day scholarship and presentation of the war.

Mr. Reed said he was not bothered by the painting’s continuing prominence and possible resurgence.

“As a black person, I’m quite comfortable with it because I know how the end of the movie turned out,” the mayor said. “The right result was reached. That doesn’t mean that we should not be privy to an expansive story of how we got to who we are today.”

But the deal that Mr. Reed helped to broker created the complicated task of moving the painting from the Atlanta Cyclorama and Civil War Museum, which closed in 2015 to prepare for a relocation that will cumulatively require about 200 people. Not long ago, a risk-management expert from the History Center’s insurer called Jackson McQuigg, the center’s vice president of properties, with a polite, terse request: “Walk me through it.”

Workers, Mr. McQuigg replied, will spend days rolling the painting, which is appraised at $7.5 million, onto a pair of 6,200-pound spools. A crane will slowly lift the spools — “We’re hoping paint-drying goes faster,” Mr. McQuigg said in an interview — through seven-foot holes cut in the roof of the nearly century-old building. Then, once the shrink-wrapped painting is resting aboard two trucks, the workers will let the clock tick.

“We’re going to wait until everybody goes home and the traffic dies down and there’s no more Atlanta rush hour,” Mr. McQuigg said in the musty room where the cyclorama has hung for generations. “Heck, it might be 3 in the morning.”

The cyclorama’s former home will be converted into an event space for Zoo Atlanta, a private nonprofit. The painting, once it has been relocated, will undergo extensive restoration efforts before its formal reopening, scheduled for fall 2018.

Among panorama proponents, the project in Atlanta, more than eight years after a restoration of the “Battle of Gettysburg” cyclorama in Pennsylvania, is seen as a crucial effort to preserve the medium’s past. Fewer than two dozen cycloramas from the late 1800s and early 1900s are believed to have survived the last century.

“It’s a chance to represent a really major and widely consumed art form that most people have really forgotten about,” said Sara Velas, the president of the International Panorama Council and the artistic director of the Velaslavasay Panorama in Los Angeles. “It’s still impactful and entertaining, even if our attention span has changed from what it was in the 19th century.”

And in Atlanta, a city that was a cradle of the Civil Rights Movement but is within sight of a state-owned monument to the Confederacy at Stone Mountain, reviving the “Battle of Atlanta” cyclorama is also a means to clarifying history.

“It’s been caught up in ‘the Lost Cause,’ and that made it a sore subject for a lot of people,” Dr. Jones said of the painting that stood nearby, shrouded in scaffolding. “We’ve got to unwrap that, and we’ve got to get past that, and we’ve got to be able to talk about ‘the Lost Cause’ objectively and talk about it for what it is and what it’s not. This is a way we can do that.”