The skyscraper at 40 Wall Street occupies a special place in Donald Trump’s tale of business success. It is, in all likelihood, the most valuable single real estate asset he controls, worth hundreds of millions. And he never gets tired of saying that he bought it for a mere $1 million in 1995. “On occasion, I am asked what my favorite deals have been,” he wrote in his book “Never Give Up.” “I have a lot to choose from, but there is something about the acquisition of 40 Wall Street that will always stand apart.”

What’s often left unsaid is that Trump doesn’t actually own the building. He merely leased it for a term of up to 200 years. The building’s actual owners are a group of obscure, wealthy Germans.

That suddenly matters a great deal. Trump will be sworn in as President of the United States on Jan. 20. The commander-in-chief owing regular lease payments to a bunch of foreign businessmen might not be concerning if it weren’t for the fact that no one seems to know exactly who they are.

Some articles on the property have mentioned in passing that the Hinneberg family owns the land under 40 Wall Street. Others mention the name Joachim Ferdinand von Grumme-Douglas. But there has been no serious effort to shed some light on the owners and the source of their wealth.

The ownership web of 40 Wall

On December 7, 1982, five Germans bought the land under the tower from its long-term owner, the Metropolitan Life Insurance Company. The buyers: Stephanie von Bismarck, Joachim Ferdinand von Grumme-Douglas and siblings Anita, Christian, and Walter Hinneberg (more on these people below).

Anita and Walter Hinneberg each owned 25 percent of the property and Christian Hinneberg owned 30 percent. Bismarck and Grumme-Douglas each owned 10 percent.

In 1992, the three Hinneberg siblings transferred their combined 80 percent interest to an entity called 40 Wall Limited Partnership. In December 2014, that entity in turn transferred its interest in the property to another entity, 40 Wall Street Holdings Corp. The beneficial owners of that latest entity aren’t public, but Christian Hinneberg signed the deed as the buyer on behalf of 40 Wall Street Holdings Corp.

Meanwhile, in 1992, Bismarck and Grumme-Douglas transferred their combined 20 percent interest to an entity called Scandic Wall Limited Partnership. In 2004, that entity in turn transferred it to another entity, called New Scandic Wall Limited Partnership, which still owns a 20-percent stake in the building. The beneficial owners of that entity aren’t public, but the 2004 deed document lists Joachim Ferdinand von Grumme-Douglas as its president. Reached by phone, Stephanie von Bismarck confirmed that she invested in the property but declined to say whether she still holds a stake. Grumme-Douglas could not be reached.

To sum up: the Hinnebergs still appear to control the entity that owns 80 percent of 40 Wall Street. Joachim von Grumme-Douglas is the president of the entity that owns the remaining 20 percent, and Stephanie von Bismarck may or may not still be a part of it.

Here’s where it gets complicated: While the Germans technically bought the property in 1982, they didn’t have full control. Since 1966, the building had been leased to investors George Comfort, Henry Loeb and Clifford Michel.

While the land stayed under German ownership the following decades, the leasehold changed hands several times. Three weeks after the property sold to the Germans, Comfort and his partners transferred the leasehold to an entity that was later found to hide the wealth of Philippine dictator Ferdinand Marcos. Following Marcos’ exile in 1986, the tower became embroiled in several lawsuits. In 1989, New York-based Resnick family took over, but amid a market downturn, they couldn’t make the building lucrative. In 1993, Hong Kong-based Kinson Properties took control of the leasehold in a foreclosure sale, but it too struggled to make the building a cash cow. In 1995, Trump took over the leasehold and restructured it.

Under the new terms, the lease runs through April 30, 2059, with two tenant’s options to extend it by 67.5 years each. Bloomberg valued the leasehold at about $550 million in 2015. Though it’s unclear how much the Trump Organization receives in annual rent, Donald Trump Jr. last year said the building was 97 percent leased. With an estimated average $36 per square foot, Trump could receive more than $30 million a year from tenants at 40 Wall Street.

A spokesperson for the Trump Organization declined to comment.

Trump, who took out a $160 million loan against his leasehold in 2015 from Ladder Capital, pays the owners $1.6 million a year under the terms of the ground lease, according to SEC documents cited by the New York Times.

So, who are the people Donald Trump writes rent checks to every year?

The Hinnebergs

Elections to the Hamburg chamber of commerce’s plenum don’t typically make headlines, but this year marks the exception. A group called “We are the chamber” is running on a platform to shake up what they describe as a crusty elite, get rid of mandatory dues and increase transparency. Sound familiar? It seems that the global anti-establishment movement that swept Trump into the Oval Office and put the United Kingdom on a path to leave the E.U. has made it into the hallowed halls of one of the merchant city’s most prestigious institutions.

But that’s not the only connection between the so-called chamber rebels and Trump: one of its leaders is Walter Jr. Hinneberg. “How Donald Trump’s friend is shaking up Hamburg,” read a German-language headline in local paper Hamburger Abendblatt on Nov. 11.

Twin brothers Christian and Walter Jr. Hinneberg, 64 years old, are among the wealthiest and best-connected ship brokers in the world. They run their business, named Walter J. Hinneberg GmbH after their late father, from a small office in Hamburg’s Ballindamm street. Like Trump, the Hinnebergs inherited a substantial business from their father and made it bigger. But in another sense they are the exact opposite of Trump: they are reserved, shy away from media coverage and live a relatively modest lifestyle considering their wealth, one family friend told TRD. “Their motto is ‘discretion is our business,’” the friend said.

While many ship brokers field flashy, corporate offices, the Hinnebergs run their business from a couple of conservatively decorated rooms with a staff of less than a dozen, one shipping industry source who personally knows the Hinnebergs said.

The source suggested that the brothers likely had some sort of involvement with the majority of container ships that roam the oceans, and have particularly strong relationships with Korean shipyards.

Both brothers live in Hamburg, but Christian spends much of his time in Zurich. According to property records, a Christian Hinneberg with the company’s address in Hamburg owns a co-op apartment at 2 Tudor Place in Manhattan. Christian is married to the daughter of the late Peter Tamm, who headed the Axel Springer publishing house between 1970 and 1991. (The firm is best known in the U.S. for buying Business Insider in 2015.)

It’s not entirely clear what inspired the Hinnebergs to invest in New York real estate, but the family friend suggested they simply saw it as a “safe bank” to diversify their holdings.

In a rare interview, Christian told the maritime news company Lloyd’s List in 2004 that with his father’s traumatic experience of losing his savings during World War II in mind, the family eschewed stocks or currency investments in favor of property, “something solid,” he said.

The Hinnebergs appear to have a good relationship with their ground tenant at 40 Wall. In a recent chat with the Hamburger Abendblatt, Walter Jr. described Trump as a “friendly and not at all arrogant person.”

Trump, in turn, has heaped praise on the family. “I got along very well with the Hinnebergs, and they realized that after a string of losers who had owned the building, I had the integrity of their spectacular property first and foremost in my mind,” he wrote in “Never Give Up.” “They are a truly great family, and they knew I loved the building, that I would be doing everything possible to restore it to its inherent grandeur.”

The friendship between the developer and the ship brokers appears to have lasted: two sources close to the family told TRD that the Hinnebergs spent the holidays with Trump at his Florida estate Mar-a-Lago this year.

And on Jan. 4, Walter Hinneberg had a 25-minute meeting with Trump at Trump Tower. According to news reports, he also had lunch with Trump’s son Eric.

Joachim von Grumme-Douglas and Stephanie von Bismarck

Stephanie Andrea Viveca Martita von Bismarck, nee Sedlmayr, married into the aristocratic dynasty most famous for producing Germany’s first chancellor, Otto von Bismarck. Her husband, Gottfried von Bismarck, holds a master of science in electrical engineering degree from MIT and spent some time working in the U.S. According to his Linkedin page, he now works as an independent business consultant. (He is not to be confused with another Gottfried von Bismarck famous for hosting drug-fueled orgies in London who died of a cocaine overdose in 2007. ) The couple, both in their 70s, lives in Hamburg.

Little is known about Joachim Ferdinand von Grumme-Douglas, other than that he was born in 1933 and lived or still lives in Brussels. According to an online genealogy tracker of the sprawling Douglas family, he is a descendant of Scottish and German aristocrats and the grandson of an admiral in the imperial German navy.

Joachim von Grumme-Douglas and Stephanie von Bismarck appear to be closely related. When Grumme-Douglas’ mother Annabel Sedlmayr (nee von Arnim, widowed von Grumme-Douglas) died in 2001, the death announcement listed Stephanie von Bismarck (nee Sedlmayr) at a spot typically reserved for immediate relatives of the deceased.

As the son of a born von Arnim, Grumme-Douglas is the scion of one of Germany’s more famous aristocratic dynasties. Arguably the best-known von Arnim was Hans-Jurgen, a World War II general who led Nazi Germany’s army in North Africa from 1942 until its capitulation in 1943.