Iconic images of Princess Diana go on display at her family's estate

— -- Some of the most iconic photos of Princess Diana have gone on display at Althorp, her family home and resting place.

The new exhibition features photographs by Mario Testino that were taken for Vanity Fair in 1997. The photos were the last official portraits of the late Princess of Wales before her tragic death that same year.

The 15 photographs in the collection were last shown in 2005 at Kensington Palace. This is the first time in 12 years the entire collection will be viewed together.

“I have always felt that Mario Testino captured the essence of Diana, quite brilliantly," Earl Spencer, Diana's brother, said in a statement on the Althorp website. "These wonderful images made a huge impact on me when I saw them first, and revisiting them now, 20 years later, seems a fitting tribute to my beautiful, fabulous, sister.”

The Althorp Estate, located about 70 miles from London, is owned by the Spencer family. Diana's grave site is located on an island at the center of the estate.

The exhibition, which opened Monday, is part of a series events to remember Prince William’s and Prince Harry's mother 20 years after her unexpected death at the age of 36.

“It’s a real privilege to have been given the opportunity to photograph someone like Princess Diana, and to have the images become symbolic of her kindness and beauty," Mario Testino said ahead of the exhibition. "I’m very happy to see them at Earl Spencer’s home, which brings her back to her family estate.”

Testino was one of Princess Diana's favorite photographers. Since Diana's death, Testino has done a number of royal commissions for Prince William, Princess Kate and Prince Harry.

He shot family photos of the christening of William’s and Kate's son, Prince George, and famously photographed William and Kate for their engagement.

Kensington Palace has announced a number of events to commemorate Diana's life this year.

Most recently, a stunning memorial garden opened at Kensington Palace to mark the 20th anniversary of Princess Diana's death and to honor her life.

A team of six gardeners and a number of volunteers spent 18 weeks planting the floral tribute of white roses, white Diana tulips, white hyacinth, forget-me-nots and other favorites of Diana’s in the sunken garden.

William, 34, and Harry, 32, have also commissioned a statue on the grounds of Kensington Palace to honor Diana.

"Our mother touched so many lives," William and Harry said in a statement earlier this year announcing the statue. "We hope the statue will help all those who visit Kensington Palace to reflect on her life and her legacy."

An exhibition chronicling Diana's evolving style during her life opened at Kensington Palace in February. The exhibition, titled "Diana: Her Fashion Story," offers a unique look at Diana's style and features some of her most stunning outfits.

Harry told ABC News' Robin Roberts before the Invictus Games last year that he and William intend to keep his mother's legacy alive.

"We will do everything we can to make sure that she's never forgotten and carry on all the special gifts, as such, that she had and that she portrayed while she was alive," Harry said in the March 2016 interview.