Princess Gloria speaks from experience.

Despite being raised a Catholic who spent summers with her grand aunt, a Benedictine nun, in the Black Forest, as a young woman she was less than serious about religion. At 19, the young aristocrat met the 11th Prince of Thurn und Taxis, the 53-year-old Johannes, before a Supertramp concert in Munich.

In 1980, she married the eccentric and bisexual nobleman, whose family made a fortune as the postal service for the Holy Roman Empire. She then became the It Imperial Girl of the ’80s, hanging out in the clubs with Mick Jagger, Andy Warhol (he “went to church every day,” she says) and really anyone else you can think of.

In 1990, her husband died, leaving her as a young widow and mother of three with hundreds of millions of dollars in debt. She got herself a business education, took the ancestral palace public, auctioned off the silver, jewels, wine and some of the art, and saved the family’s fortune.

She credits the turnaround to “the grace of God” that convinced her “that I have to give something back.” She became more devout and befriended clergy, including Joseph Ratzinger, the future pope Benedict. But she was far from cloistered.

She remained a New York high-society staple who this year celebrated Oktoberfest with the Clintons and was one of the roughly dozen women to attend Mrs. Clinton’s pre-2016 Election Day birthday party. (“A great woman,” the princess said, declining to share details. “It’s too early, in 10 years.”)

And Princess Gloria still likes to go fast.

In a golf cart (though not “the Rolls Royce of golf carts,” which she keeps in Rome), she zipped around the lush gardens, the medieval rectory where she feeds the poor, the stately courtyards and the recently refurbished wings of her castle.

She said that if a local university were game to foot the bill, her place would make far better classrooms for a Gladiator School than a cold monastery outside Rome.

“You see these, there is plenty of space for a school here,” she said. “And it’s heated!”