Eugenie and Jack Brooksbank are to marry Friday at St. George’s Chapel, which is part of the castle complex.
The nuptials will draw most senior members of the royal family, including Eugenie’s grandmother, Queen Elizabeth II.
The couple will marry in the same venue used in May by Prince Harry and Meghan Markle, who is now known as the Duchess of Sussex.
Eugenie, 28, is ninth in line to the British throne. She works in the art world.
Her sister, Princess Beatrice, will be maid of honor.
They are the daughters of Prince Andrew and Sarah Ferguson.