Princess Diana
Picture dated 14 Nov. 1992 of Princess Diana leaving the first anti-AIDS bookshop in Paris. Getty Images

Thursday marks the 20th death anniversary of one of the world's most iconic figures, Diana, Princess of Wales — Prince Charles' first wife and mother of Prince William and Prince Harry.

Her brother Charles Spencer referred to her as "the unique, the complex, the extraordinary and irreplaceable Diana." She is still fondly remembered by millions across the world as the "people's princess" for her down-to-earth nature.

On Thursday, people paid their tribute to Diana and placed photos and personal messages at the gates of Kensington Palace in London. Diana died two decades ago, leaving a void and triggering a flood of grief among people in the United Kingdom, and others around the world, who admired her.

Her admirers in the U.K. had begun paying tribute to the Princess of Wales at the time she died, even before dawn, by placing candles shaped in the letter "D'' at the gates of the Kensington Palace, her home.

"We had never met her and been nowhere near her, but I think she touched so many people because of who she was, the way she conducted herself in the context of where she was living and who she became," said Mara Klemich, 55, a royal well-wisher from Australia, according to

Prince William and Prince Harry honored their mother on Wednesday at Kensington Palace as they visited a garden where Diana used to take a stroll and ask the gardeners about the ever-changing display of the garden. Both the princes and the Duchess of Cambridge met the well-wishers after the walk, but they are not scheduled to take part in any engagements on Thursday.

Diana died on Aug.31, 1997 after her car crashed into a concrete pillar in the Alma Tunnel in Paris, while traveling at a speed more than 60mph (100kph). She was being chased by paparazzi. Her lover Dodi Fayed and their driver Henri Paul, who also accompanied her, were also killed. Her bodyguard Trevor Rees-Jones, who was also in the car, was injured but survived the crash.

She was born as Diana Frances Spencer on July 1, 1961, and became Lady Diana at the age of 14 when her father, John Spencer, became the eighth Earl Spencer in 1975. Diana, who grew up among British aristocratic families and thus was familiar with their ways, married Prince Charles, first in line to the British throne, in an elaborate ceremony in 1981 at St. Paul's Cathedral in London.

Prince Charles and the Princess of Wales divorced in 1996, but Diana remained famous among her former subjects. Throughout the years of performing her duties as a princess, she was well-known for her philanthropy and dedication toward charities, especially HIV and AIDS research. "I'd like to be a queen of people's hearts, in people's hearts, but I don't see myself being the queen of this country," Diana once said, adding, "I don't think many people will want me to be queen."

It is said the princess is buried on an island in an ornamental lake called "The Oval within Althorp Park's Pleasure Garden," where visitors are not allowed, the Telegraph reported. However, the exact location of her grave has never been disclosed to the public.

To mark the occasion of her 20th death anniversary, here are 15 iconic photos of the "people’s princess."

The Prince and Princess of Wales, Prince Harry, and housemaster Dr. Andrew Gayley (behind) escort Prince William (second from right), second in line to the throne, for his first day of term at the world famous Eton College, Sept. 6, 1995. REUTERS
Iconic Images Of Princess Diana
Princess Diana watching Wales lose in the 'France v Wales' match during the Five Nations Championships at Parc de Princes in Paris, January 1995. Getty Images
Iconic Images Of Princess Diana
Princess Diana and her friend Elizabeth Tilberis, Editor-In-Chief of Harpers Bazaar, at the CFDA gala, January 1995. The Princess wore a sleek sleeveless navy column. Getty Images
Iconic Images Of Princess Diana
Diana, Princess of Wales, on a walking tour of the Northwestern University campus in Evanston, Illinois, June 1996. Getty Images
Iconic Images Of Princess Diana
Princess Diana visits the National Children's Hospital in Tokyo, February 1995. Getty Images
Princess Diana, Prince Charles
Princess Diana and Prince Charles watch an official event during their first royal Australian tour 1983 In Newcastle, Australia. Patrick Riviere/Getty Images
Princess Diana of Wales talks with Mother Teresa's second-in-charge, sister Lynne Frederick during her 45-minute visit to the home of the 81-year-old Nobel laureate in Calcutta, Feb. 15, 1992. Getty Images
The Princess of Wales (C) heads out into the surf as her sons William and Harry and Lady Catherine Soames (L) enjoy the waters of Indian Castle Beach, during the vacaction on Nevis, West Indies, Jan. 1, 1993. Getty Images
Princess of Wales departs London health club, Nov.20, 1995. Getty Images
Lady Diana Spencer stands at the 41st annual United Cerebral Palsy Awards gala in New York City, Dec. 11, 1995. Getty Images
Picture of Lady Diana, Princess of Wales, with Prince Charles of Wales at their wedding at St Paul Cathedral in London, July 29, 1981. Getty Images
Princess Diana (L), Prince Harry, (C) and Prince William (R) gather for the commemorations of VJ Day in London, Aug. 19, 1995. Getty Images
Princess Diana of Wales shares a light moment with Portuguese President Mario Soares at a banquet at the Ajuda Palace in Lisbon, Portugal, Feb. 12, 1986. REUTERS
Princess Diana greets well-wishers during her trip to a park in Burnaby, Canada, May 6, 1986. REUTERS/Mike Blake
Prince Charles and Princess Diana stand on the balcony of Buckingham Palace in London, following their wedding at St. Pauls Cathedral, June 29, 1981. Reuters