As we approach the 18th anniversary of Princess Diana’s death, several unpublished photos shot at Buckingham Palace the day she wed Prince Charles are now being auctioned off.

USA Today noted that the 14 rare pictures were taken on July 29, 1981 by late photographer Patrick Lichfield and show a behind-the-scenes look at the bride and groom.

The collection consists of seven black-and-white photos and seven in color. Each of the color photos bear official Lichfield labels for copyright purposes.

"These are original prints. The black and white ones were printed by me, in the dark room in Aubrey Walk, within hours of the wedding," Lichfield’s assistant said in the letter of provenance on the auction website. "To my knowledge, none have ever been published. Very few people have ever laid eyes on them."

The photos will go to the highest bidder when they are auctioned off next month.

Princess Diana and her male companion, Dodi Fayed, were fatally injured in a car crash in Paris on August 31, 1997.

Image courtesy of Credit: Zak Hussein/INFphoto.com