Spain’s flamboyant Duchess of Alba has died aged 88 after a short bout of pneumonia. Born in Madrid on 28 March 1926, the duchess – whose full name was María del Rosario Cayetana Alfonsa Victoria Eugenia Francisca Fitz-James-Stuart y de Silva – died on Thursday morning in her home, a 15th-century palace in Seville, with her six children and husband at her side.

“Cayetana always had Seville in her heart and for this reason she will always remain in Seville’s heart. May she rest in peace,” tweeted Seville’s mayor, Juan Ignacio Zoido, referring to the duchess by the name she was known by in Spain.

Flags flew at half-mast in Seville, and Thursday was declared a day of mourning. The funeral will take place on Friday afternoon in Seville’s gothic cathedral. Her body will lie in state in the Andalusian capital, Spanish media reported.

Throughout the day, many across Spain paid tribute to the duchess. King Felipe VI and Queen Letizia called the duchess’s family to convey their condolences and sent wreaths, while Socialist politician Alfonso Guerra remembered the aristocrat as “a liberated and courageous woman who took the world by storm”. Madrid’s conservative mayor, Ana Botella, described her as “a great Spanish woman who was loved by all of the world.”

The duchess’s outspoken nature made her a mainstay in Spain’s gossip press. In 2011, she raised eyebrows around the world when, aged 85, she announced plans to marry Alfonso Díez, a civil servant 25 years her junior.

The announcement of her marriage plans provoked a family feud, with her children accusing Díez of being a gold-digger who was only interested in her fortune, estimated to be up to €3.5bn (£2.8bn).

The duchess and her new beau fought back against the claims, with Díez signing a document renouncing all claim to her wealth.

“Alfonso doesn’t want anything. All he wants is me,” she told reporters. When that failed to calm the storm, the duchess made her will public, dividing up her land and castles among her six children, before the marriage.

Still, the squabbling continued, leading the duchess to accuse one of her daughters-in-law live on TV of being “lying, wicked and covetous”. Months later, the duchess married Díez, dancing a quick few steps of flamenco in front of the adoring crowds that gathered outside the Dueñas palace in Seville on the day of the wedding.

Along with her 49 inherited aristocratic titles – making her the noble with the most titles in the world according to Guinness World Records – the duchess owned vast amounts of property and an art collection that included paintings by Goya and Velázquez, a first edition of Don Quixote, Columbus’s first map of America and the last will and testament of Ferdinand the Catholic, father of Catherine of Aragon.

The duchess dancing at her wedding in 2011. Photograph: Picasso Carlos/Sipa/Rex

Depicted by Spanish media as an eccentric rebel aristocrat in recent decades, the duchess embraced the role, sharing stories of how she once declined to be a muse for Pablo Picasso and privately taking delight in 2011 when a magazine published topless pictures of her, taken when she was in her 50s, on an Ibiza beach.

“I am not a person who allows herself to be managed,” she once told Hola! magazine. “I have my own ideas and I try to convert them into reality.”

The duchess also claimed the title of Duchess of Berwick and was a distant relative of King James II, Winston Churchill and Diana, Princess of Wales.