Perched on a steep hilltop in southern Germany, the striking turrets of Hohenzollern Castle rise in contrast to the rolling countryside that surrounds them. The fortress is the ancestral seat of Germany's last imperial family. If the country still had a monarchy today, the castle's owners would be its royal family, led by Georg Friedrich, whose ceremonial title is also his legal surname: Prince of Prussia.

Inside, the would-be Kaiser Prince Georg cranes his neck towards an ornate family tree painted on the wall behind him. He proudly describes his lineage, which traces back through centuries of kings and queens who ruled over Prussia (a once-vast area that included parts of modern-day Germany, Poland, Lithuania, Russia and Denmark) through German monarchs like his great-great-grandfather, the Kaiser who led the country into World War I.

The case was first filed decades ago, but it has recently provoked ire and outrage among the German public, many of whom believe he's entitled to nothing at all. And some historians are skeptical of his claims.

"I see it as my duty," he tells CNN, in his first ever TV interview on the subject. "I think my family would fully agree to pursue these claims, whether the judges will eventually judge in our favor or not."

Standing between Prince Georg's family and a cache of untold monetary and cultural value is a broadly worded German law that disqualifies those who helped the Nazis into power from restitution or compensation for lost property. To understand today's legal wrangling, you have to go back more than a century into a grim chapter of German history.

In 1918, following defeat in World War I, the country ditched its royal family to become a republic and a democracy. The then-Kaiser and his family gave up their power but got to keep a substantial part of the fortune they'd amassed over the centuries: castles, land, artworks, crowns, swords and jewels. The ex-royals then went into exile in the Netherlands.

After World War II, Germany was divided into west and east, with the communist Soviet Union and the German Democratic Republic taking control of the latter and seizing the property of ordinary citizens and ex-royals alike. The vast majority of the then-privately-owned German royal fortune fell on the wrong side of the Iron Curtain. It would take almost half a century for the Berlin Wall to come down.

Shortly after, in the 1990s, a reunified Germany passed a law allowing anyone whose property was expropriated to reclaim it. Millions of ordinary families that had fled East Germany used the legislation to reclaim their homes. But the law came with a very specific catch: Those who "substantially supported" the Nazis were ineligible.

This all means that a complex legal claim being debated in 2020 hinges, ultimately, on the actions of one man in the 1930s: Prince Georg's great-grandfather (and the son of Germany's last Kaiser, Wilhelm II), Crown Prince Wilhelm.

The result has the potential to shift large portions of museum collections from public to private hands.

"A court decision brings with it the danger of a decision in favour of the House of Hohenzollern and, in the worst-case scenario, of the large-scale removal of objects from the collections of cultural institutions," a spokesperson for the German Ministry of Culture told CNN by email. "An out-of-court settlement, by contrast, would likely make it possible to avoid lengthy court proceedings and would provide a viable foundation for cooperation between the House of

Hohenzollern and the affected cultural institutions."

Asked if Prince Georg's claims are justified, a spokesperson for the Berlin Senate Department of Culture told CNN in an email, "The political answer is no.

From a legal point of view, things can look different. That is the only reason for the talks."

And beyond the historical treasures at stake, the case ultimately gives rise to a question German society has long grappled with: how to judge the sins of your ancestors.

A uncomfortable family photo

At Hohenzollern Castle, Prince Georg is shown a photo he's seen before: It's his great grandfather Crown Prince Wilhelm, in 1933, dressed in a military uniform and a Nazi armband. He's standing above a large swastika at a rally of 80,000 members of the SA, a Nazi paramilitary group. By this time, Wilhelm had returned from exile on the condition that he wouldn't involve himself in politics -- a promise he apparently couldn't keep.

"It's very hard to look at," Prince Georg says. "These pictures are very strong. Especially when you see the swastika on his arm. It always makes your breath stop, and you ask yourself, 'Why is he wearing that?'"

In the 1930s, Communism was a rising force around the world and the Great Depression had plunged people into poverty, drawing many Germans towards Adolf Hitler's nationalist agenda. Germany had been a fragile democracy for barely a decade when Hitler was elected Chancellor in 1933, the year Wilhelm was photographed in the Nazi armband. There are other photos like it, including one of the Crown Prince locked in a momentary gaze with a grinning Hitler.

Prince Georg says his great-grandfather may have been wearing a swastika, but his primary motivation was to return the monarchy to power -- and he believed Hitler could make that happen. The Nazi leader may have even entertained the possibility. A British newspaper reported in 1932 that he was secretly plotting, upon his election, to tear up the newly-enshrined democratic constitution and form a government "with the ex-Crown Prince at its head."

"The Crown Prince was driven by the idea of getting back monarchy or getting back to the throne," Prince Georg says of his great-grandfather. "But he was also misled by the idea that it might be a better to appease the Nazis, at least at the beginning."

It soon became clear that Hitler had no plans to hand over power to anyone. The Daily Mirror reported the Crown Prince was "disappointed at Hitler's changed attitude towards the monarchy," though he continued publicly supporting him nonetheless.

"He thought that it might help to keep the (Nazis) in control and lead them (down a different path), which might be more fortunate for our country," Prince Georg said. "And judging from now, this was a horrible misconception."

Rather than enabling Hitler's rise, Wilhelm and the ex-royal family was, according to Prince Georg's reading, "seen as a constant threat" due to their ongoing popularity with some segments of the public. Proof of this, he says, can be seen in 1940, when tens of thousands of people took to Potsdam's streets to mourn the death of the Crown Prince's son. Or in 1944, when Hitler's secretary recalled that, following a failed attempt on his life, Hitler said, "believe me, it will come out that the real instigator is the Crown Prince!" He wasn't, and Hitler's paranoia is well documented. But Hitler's suspicion proves he saw the Crown Prince as a threat, not an ally, Prince Georg says.

"He was in a very difficult position because...If he had shown more opposition -- which he is now blamed for not doing -- I have no idea whether I would be sitting here," he says, explaining that a distant uncle was sent to a concentration camp for doing just that.

Yet, Prince Georg also argues that Wilhelm had neither the power nor the clout to prevent the dictator's rise.

"By this time, the Crown Prince lacked the political influence to substantially contribute to the rise of the Nazi regime," said Prince Georg.

This was the very position taken by Chris Clark, an historian at Cambridge University's St Catharine's College, in a 2011 research paper commissioned by Prince Georg's family, the House of Hohenzollern.

"This is a disempowered former prince," Clark told CNN. "He was not widely respected. He was a playboy... he liked the look of Hitler, he was quite sympathetic with the Nazi party, but he didn't actually become a card-carrying Nazi.

"(Crown Prince Wilhelm's) lack of political talent, his lack of a powerful network and his lack of an official position from which he could wield power meant that, as much as he might want to help Hitler, his help wasn't especially effective."

That didn't stop the Crown Prince from trying. In a New York newspaper column published in 1933, Wilhelm praised Hitler's "clear-sighted and energetic leadership" and blamed communists and Jews for Germany's tattered reputation.

In his paper, Clark concluded that although the Crown Prince undoubtedly supported Hitler, his support wasn't "substantial." In other words, the Hohenzollerns ought to be entitled to compensation.

Evolving historical evidence

Plenty of experts have disagreed with Clark -- hinting at the complexity of this longstanding legal battle. Now the Australian-British historian says he has changed his mind, citing newly-uncovered evidence showing that the Crown Prince had more public influence than originally thought.

"That's what happens in history," he says. "We find out new stuff, we change our mind."

This new evidence was unearthed by Stephan Malinowski, a historian at the University of Edinburgh whose research has concluded that the Crown Prince significantly contributed to the Nazi regime. Malinowski, who declined to be interviewed for this story, is one of four historians commissioned by the government and Prince Georg's family to investigate the relationship between Wilhelm and the Nazis.

CNN interviewed five additional historians for this story, four of whom now side with Malinowski, though most also agreed that neither side's case is iron-clad. Among them is John Rohl, who said that the Crown Prince had once bragged "that he had actually transposed 2 million votes to Hitler," and Stephanie
Middendorf, who argues that he helped make the Nazis more palatable to the upper-class elites he rubbed shoulders with.

But there are others who support Clark's original position -- historians like Wolfram Pyta, whose 155-page research paper, also commissioned by the House of Hohenzollern, concluded that the Crown Prince "actively rejected the Nazi system." Or, independent historian Benjamin Hasselhorn, who told CNN that the Crown Prince "did provide support [to the Nazis] but not substantial support."

The 1994 compensation law effectively ensures that the German government isn't forced to compensate industrial giants -- like Volkswagen and BMW -- who supported the Nazis' rise to power and relied on forced labor from concentration camps, to build cars during WWII. Both companies have acknowledged their historic responsibility and paid compensation to victims.

But the law's intent is unclear when it comes to former royals. In the 1800s, before Germany was a country, the region was comprised of many smaller kingdoms, each with their own royal, or noble, families. Some of them have already quietly secured restitution for property and land lost during communist rule in East Germany, like Michael-Benedikt Prince von Sachsen-Weimar-Eisenach, who in 2003 dropped his claims for restitution of art works, manuscripts and the inventory of the Wartburg Castle near Eisenach, in return for €15.5 million ($18.2 million).

Cultural collateral

According to Prince Georg, the thousands of items on the line range from a simple coffee spoon to centuries-old works of art. Items that ended up outside Germany or were otherwise lost also form part of the negotiations, in case they eventually re-surface. His family is also seeking cash compensation of €1.2 million ($1.4 million), which represents the value of their land at the time it was seized.

According to the Prince's spokesperson, "It is safe to assume that the current value of the family ́s private property taken by the communists is several hundred times higher." Berlin state authorities meanwhile told CNN that the overall value of the Hohenzollerns' claim is "high, but not quantifiable."

There is no longer any property at stake, though the Prince recently settled his claim for the ancient Rheinfels Castle on the condition that the charity run by his wife receives a portion of ticket sales.

Complicating matters for the German government is the fact that Prince Georg is also the largest lender of art to cultural institutions in the German states of Berlin and Brandenburg (both facing legal claims along with the federal government) including the many paintings, furniture and other items on display at Charlottenburg Palace. He owns the crowns of the first Prussian King and Queen, which are displayed alongside an orb and scepter that he's seeking to have returned. He also owns the jewel-encrusted tobacco boxes that once belonged to Frederick the Great, the longest serving Prussian King.

The Prince says he's committed to keeping the disputed items on public display, regardless of whether they eventually change hands. "I really strongly feel this cultural responsibility to contribute something to the country and to show these items to the public," he says. "Actually, we are on the same side as the government."

He insists his claim is not about money.

"If it was that easy, I think my ancestors would have sold this place, the Castle Hohenzollern... and we would have sold our (remaining) art collection, which we lend to Berlin and to Brandenburg" he said. "It's not as simple as just taking a check."

Yet, he may face an uphill battle convincing a skeptical German public of his charitable motivations. And while the case has been quietly ongoing for decades, it has recently become a matter of public interest, thanks in part to Jan Böhmermann, host of a satirical program akin to "The Daily Show."

In the half-hour segment, the late-night comedian roasted Prince Georg for having the "balls of steel" to bring his demands to court. The comedian also dismissed his claims as outrageous and hypocritical, given that genocide victims in Germany's former colonies under the royals' rule were never compensated.

High-profile clashes

Prince Georg has also been criticized for his public handling of the case. His legal team has filed at least 30 warning letters and lawsuits, primarily targeting historians and journalists, since the case became public. Historian Eckart Conze says he was served with a lawsuit after criticizing the Prince for serving too many lawsuits. Specifically, he says the Prince's lawyers took aim at his claims that the legal threats were an attempt to "suffocate an important and necessary public debate."

Conze says he had a choice: refrain from making similar statements or prepare for a legal fight. The historian chose the latter and is awaiting his day in court, though many of his colleagues have kept quiet because they can't afford to do the same, he says. A German non-profit called the Open Knowledge Foundation is currently crowdfunding for the legal defense of journalists and historians who say that they have been threatened by the Hohenzollerns' lawyers.

"This debate really belongs in the public and it cannot, and should not, be suffocated by legal action," Conze says.
Prince Georg insists that he's never sued over critical reporting, only false or defamatory statements.

"I think it is very important to have the freedom of the press, as it is part of our constitution. And it's also a pillar of our democracy. But lying is not, and that was the only thing we tried to straighten."

Asked if he regrets his public handling of the case, he says, "We could have been better on that, yes."

Negotiating positions

The would-be Kaiser -- who is also 202nd in line to the British throne according to royalty expert Marlene Koenig -- says he hasn't sought out attention, but the legal wrangling has made it impossible to avoid. When he first took over as head of the House of Hohenzollern at age 18, he initially wondered if he wanted the responsibility at all. But his grandfather asked him to continue the restitution case, he says, a promise that still motivates him today.

"I feel obliged to fulfill his last will because he also wrote very explicitly in his testament that he expects me to follow his footsteps," he said.

But this case is, now, much bigger than Prince Georg or his grandfather. Beyond the moral question of how the legal system ought to judge the transgressions of the Crown Prince, it encourages a broader national discussion in a country that is still reconciling the past. Germany is, after all, still putting accused Nazi war criminals on trial 75 years after the end of the World War II. By asking whether Crown Prince Wilhelm facilitated the Nazis' rise, Prince Georg also thinks Germans ought to ask who else was responsible. What about the millions who voted for them? Or the big businesses who supported them?

This is, Prince Georg says, a national debate that's yet to be resolved." (Our claims) are not the reason for the discussion... I think we are kind of a symptom for the whole discussion -- or the discussion that needs to take place," he says, clearly hoping the historical debate won't distract from Germany's more recent legal traditions: to judge a case based on the law, not society's evolving moral standards. "I'm very happy that I live in a constitutional state."

For now, neither the prince nor the Brandenburg government appear willing to risk an all-or-nothing outcome by taking the case to court. Both sides recently agreed to delay court proceedings, which were due to begin in August, for another year to give them more time to reach a negotiated settlement