The Mercedes-Benz Superdome was quietly added last month to the National Register of Historic Places — a distinction that underscores the role the stadium has played in the world of sports as well as in the history of New Orleans and its recovery following Hurricane Katrina.

But in an intriguing twist, the National Park Service added the 40-year-old structure to the list over repeated objections from the state, which expressed concern that the designation, however prestigious, would complicate future renovations and the “perpetual cycle of capital investments” that have burnished the Superdome’s appeal as a site for major sporting events like the Super Bowl.

The state agency that oversees the Dome, the Louisiana Stadium and Exposition District, reiterated its ambivalence Tuesday, saying officials would “continue to investigate the effects” of the listing.

“It is our understanding that there is a procedure ... for the removal of properties from the National Register,” the agency said in a statement. “However, without a thorough evaluation of the impact of this designation on the Superdome’s operations and future maintenance and improvements, it is premature to make a decision regarding any such removal.”

Preservationists were largely taken aback by the LSED’s opposition, saying the designation would be unlikely to prevent needed changes to the Dome or even its demolition should the state deem it necessary to build a new stadium in its place.

They said the Dome’s inclusion on the register will open the window for certain tax credits that can be used toward its upkeep.

“I can’t imagine that their hands would be tied so much that you wouldn’t want something so historically significant to be protected,” said Fairleigh Cook Jackson, executive director of the Foundation for Historical Louisiana. “I think if you’ve truly got an architect that understands well-built historic structures, they find ways to make the renovations, to do the things their clients need to have done while preserving the integrity of historic structures.”

The listing, which was first reported Tuesday by The Times-Picayune, marked a triumph for Amanda Keith, a recent Tulane School of Architecture graduate who began nominating the Superdome for the register while pursuing a master’s degree in preservation studies.

The project, which Keith described as “neither quick nor painless,” stemmed from a classroom exercise intended to give students an idea “of what it would take to write the nomination.”

“It’s a lot of research,” she added. “You end up with almost a thesis worth of material.”

Sold on its architectural allure and importance to the city’s history, Keith selected the Superdome from a list of candidates compiled by the Louisiana Office of Cultural Development.

In the registration form she authored months later, she touted the Dome’s role “as a shelter of last resort for the people of New Orleans during Hurricane Katrina in 2005” and its reputation as “an exceptional multipurpose entertainment venue, hosting the most Super Bowls of any stadium as well as various sports and entertainment events ranging from basketball to pro wrestling to a record-breaking Rolling Stones concert and the Republican National Convention.”

In July, as Keith was preparing to present her proposal to the Louisiana National Register Review Committee, the Louisiana Stadium and Exposition District made its opposition to the listing known.

Ron Forman, the agency’s chairman at the time, wrote a letter to the State Historic Preservation Office warning that inclusion on the National Register “could potentially adversely impact our ongoing obligation to ensure that the Superdome is maintained as a world-class multipurpose venue.”

Forman, citing a “demanding event schedule,” added that capital projects at the Dome are managed “on the tightest of schedules.”

“Additional comment periods and approvals associated with a National Register of Historic Places designation would likely limit our ability to meet our already tenuous deadlines,” he wrote.

The agency opposed the designation again in December, asking that the Superdome “not be recommended for enlistment on the National Register.”

Caroline Downer, the communications director for the Office of Cultural Development, said Tuesday that “there are really no disadvantages to being listed.”

The opposition, Keith said, was rooted in “a false conception that people think they’re not going to ever be able to make changes to the building.”

Listing on the register “doesn’t prevent a building from being torn down, unfortunately,” Keith added. “It incentivizes making historically appropriate changes, so unless they wanted to do something really crazy to the building like take the dome off, or change the complete outside of the building, they would be allowed to make any changes they’d want to make.”

Bill Curl, who served as the Superdome’s spokesman from 1977 to 2010, said the national designation is further proof that the stadium, at 40 years old, “has become a national icon in the sports world and is recognizable throughout the country.”

“When you look at other facilities that are on that list, it’s a prestigious group,” Curl said. “The architecture still looks like it’s something from the future.”

The new membership of the Louisiana Stadium and Exposition District, chosen recently by Gov. John Bel Edwards, will hold their first meeting at 1 p.m. Wednesday at the Dome.

Follow Jim Mustian on Twitter, @JimMustian.