It is the age-defying romance that caught the world's attention.
And now – with little more than a month left to go before her wedding, the Duchess of Alba has opened up about the younger man who has stolen her heart.
Spain's well-loved aristocrat gave an exclusive interview to HELLO! magazine's sister publication HOLA!
In it, she describes Alfonso Diez Carabaotes, whom she has known for three decades, as "fantastic".
"He is a wonderful person," she adds of the civil servant – who, at 61 is 24 years her junior.
"He is the person who has completely changed my life."
When asked if her beloved has any faults, the 85-year-old answers: "He has a strong temper."
She adds: "But I do too. What happens is we both get over it pretty quickly."
The couple first met over thirty years ago. But their romance started up after a chance meeting in Madrid.
"I was coming out of the cinema, and he was going in to see the same film," remembers the Duchess, whose first name is Cayetana.
"That's how it all started."
The couple first faced opposition from the Duchess' children. But after she divided up her vast inheritance between them the wedding will go ahead in October.
"I did it because I wanted to. No one forced me," she says when asked about the inheritance. "Anyway, while I'm alive everything is still in my hands."
A small intimate ceremony will take place in the chapel of Cayetana's majestic Seville residence, Las Dueñas palace.
It will start at 1pm and will be attended by close family and a small number of friends, including the bride's surgeon – Doctor Trujillo.
But the date hasn't been set yet.
"It will go ahead in October, this we know," says the Duchess. "It depends on when it's convenient for all."
With Cayetana's playful sense of style – and love of bold prints and colours – the dress is bound to be spectacular.
But it seems there's still lots to be decided on.
When asked by HOLA! what colour it will be, she answers: "I don't know."
"I won't know until I get to Seville and talk to Victorio and Lucchino and we decide," she adds, referring to the Seville-based designers who are making her gown.
As for jewellery, she's planning to keep it simple.
She'll wear "some earrings. And nothing else."
After becoming man and wife, the newlyweds will reside in Seville. Alfonso has taken an extended leave of absence from his job in the Ministry of Employment in preparation.
"He'll look for a job in Seville," says the Duchess. "We have so many friends there I doubt it'll be difficult to find one."
More on the Duchess' incredible love story