Obama Center isn't a traditional presidential library. Critics say it's an activism center.

Don't call it a library.

While every other modern presidential library houses that former commander-in-chief's papers for public viewing, the Obama Presidential Center has no such component. Instead, Obama's presidential records are being stored elsewhere, though digital versions may one day be available there.

At its core, the center serves two purposes: a museum dedicated to Obama's presidency and the headquarters of the Obama Foundation, Obama's private nonprofit organization.

Signs reading "Bring Change Home" and "A Home For Action" surround the perimeter of the campus. The messaging mirrors how the Obama Foundation has described the center in its annual reports - not as a traditional presidential library, but as a "campus" and "living institution."

"We are building more than a campus. We are creating a living institution that will inspire, empower, and connect the next generation of leaders," the foundation's 2024 annual report reads.

The center, which as of 2021 had cost well over $800 million and is believed to have eclipsed the $1 billion mark, is a departure from presidential libraries, in both scale and purpose.

Troy said the direction did not surprise him.

"Obama was a community organizer. He's an activist. That's how he came up, and it doesn't surprise me that he wants to go in this direction," Troy said.

Obama himself offered a glimpse into how he views the center's mission during Thursday's opening ceremony.

"This center is devoted to lifting up their stories, giving them the tools and support they need to expand their impact," Obama said.

Obama later underscored that mission in his speech.

"While we are non-partisan, we are not value-neutral. We have a point of view," he said

Critics say Thursday's ceremony confirmed what they feared all along: The center seems designed not just to preserve Obama's presidency, but to carry his vision into the future.

The center's opening has reignited debate over whether the project evolved far beyond the traditional presidential library model for which many Chicagoans originally believed they were handing over their historic parkland.

The public land fight

Opponents argue that transferring public parkland to a private foundation violated the public trust doctrine, a legal principle intended to preserve public assets for the public benefit.

Those challenges were ultimately unsuccessful in court, although critics note that the central public trust arguments were never fully tested on the merits.

"When we were defeated, we weren't told that we were wrong on the merits," Richard Epstein, a New York University law professor and one of the nation's foremost experts on the public trust doctrine, who represented the local Protect Out Parks group.

"We were told that we had no right to bring the complaint at all."

The Chicago City Council approved the deal with Obama, but Epstein said lawmakers were not free to simply set aside the public trust doctrine.

"The public trust doctrine is meant to be a restraint on the legislature," Epstein told Fox News Digital. "This has been an epic frustration."

Epstein warned that handing over public land without fully vetting the foundation's finances could expose taxpayers to future risks if the center encounters financial trouble down the road.

WATCH: NYU law professor Richard Epstein says courts never ruled on key Obama Center claims

Critics also point out that the public land transfer was only part of the taxpayer contribution. Hundreds of millions of taxpayer dollars were spent on surrounding road, utility and transportation improvements tied to the project. Supporters say those upgrades modernized the area, but opponents argue they were done to serve a privately run institution.

Bait and switch?

"This isn't a presidential library. It's a Democratic headquarters on the South Side," Grogan told Fox News Digital outside the facility.

Grogan described the shift as a classic Chicago politics bait-and-switch.

"They go and sell it with the most palatable thing," Grogan said. "Then they just incrementally, drip by drip, make it worse until they get back to the reality."

"It's not just a museum. It's the home base for the foundation and everything it does," he added. "They're not going to go and pay rent someplace else when they're going to have this big mausoleum here to go and hold their meetings and plot their plans."

That means the foundation - not the federal government - decides how the center is run, what exhibits visitors see and how Obama's legacy is presented.

The campus does include a branch of the Chicago Public Library.

WATCH: Illinois GOP chair says Obama Center is political operation on public land

Troy: A mixed verdict

Troy said presidential libraries have evolved over time and that making records available digitally could ultimately benefit historians if the system works as intended. Presidential researchers like himself may no longer need to travel across the country to review presidential records, he noted.

Troy also acknowledged that presidents have traditionally had broad discretion over the non-archival portions of their presidential libraries.

"At the end of the day, presidents raise the money for these things and they have leeway to do what they wish with that part of it," Troy said.

"It's not the direction I would choose, but he raises the money," Troy said. "He gets to do what he wants."

But Troy cautioned that the center should not lose sight of the traditional purpose of presidential libraries.

"I worry about getting too far afield from the purpose of what these things are supposed to be, which are memorials to a presidency and a repository for all their documents," he said.