The Duchess, whose full name was Maria del Rosario Cayetana Fitz-James Stuart y Silva (but was generally referred to as Cayetana), was a tabloid darling for her outrageous fashions, frizzy coif, and unabashed fondness for plastic surgery and bikinis, well into her 70s and 80s.
In 2011, the one-of-a-kind aristocrat raised eyebrows when she exchanged vows with third husband Alfonso Diez, a civil servant 25 years younger than her. She created lasting memories at the wedding when she pulled up her dress and showed off her flamenco dancing skills.
In recent years, her heath had waned, as she cracked her pelvis in 2011 after a slip-and-fall at the palace, and suffered a broken femur when she fell in Rome last year.
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The royal, who was officially recognized by Guinness as the world's most titled noble, left behind a $3.5 billion fortune to her six adult children.
"May she rest in peace," Seville mayor Juan Ignacio Zoido tweeted Thursday.