Harry and the former Meghan Markle recorded their memories of the wedding for an audio commentary that is part of the new "Relive the Royal Wedding" exhibition at Windsor Castle that opens Friday.

The gown is set to be the prime attraction at the 10-week display.

In the audio recording, the former actress said she worked with Keller to create a "timeless" gown with a "classic feeling." The dress also needed to be suitably modest for the May 19 wedding held in a chapel on the grounds of Windsor Castle, she said.

"There was a great level of detail that went into the planning of our wedding day," the duchess said.

"I think for us, we knew how large the scale of the event would be, so in making choices that were really personal and meaningful, it could make the whole experience feel intimate, even though it was a very big wedding," she said.

Meghan described the "incredibly surreal day" when she and her fiance visited Queen Elizabeth II, Harry's grandmother, to choose a tiara for her to wear during the wedding ceremony. She picked Queen Mary's diamond and platinum bandeau tiara from the queen's collection. It is featured in the new exhibit.

For his part, Harry said it was "very sweet" of his grandmother to lend his bride-to-be the priceless headpiece.

Harry's wedding outfit, including the frockcoat uniform made by master tailors on Savile Row, is also display, though likely to be overshadowed by Meghan's gown and the tiara.