WATCH: Tributes to Princess Diana 20 years after her death

Her sons Princes William and Harry have visited floral tributes

WATCH: Tributes to Princess Diana 20 years after her death

File photo of Diana, Princess of Wales during a visit to Leicester | Image: John Stillwell/PA Wire/PA Images

Tributes have been left at the gates of Kensington Palace in London, where thousands came to mourn the death of Princess Diana 20 years ago.

On August 31st, 1997 it was announced that Diana, Princess of Wales had died after a car she was travelling in crashed in the Pont de l'Alma tunnel in Paris.

She was 36-years-old.

To mark the 20th anniversary of her death people have stuck posters to the gates of Kensington Palace, and left bunches of flowers to remember her.

Photos from the time show how in the week following her death a sea of flowers were left in front of the gates of the palace as people travelled from across Britain and around the world to pay their respects.

Grieving visitors view the thousands of floral tributes laid outside Buckingham Palace, following the tragic death of Diana, Princess of Wales  in 1997 | Image: John Stillwell/PA Archive/PA Images

On Wednesday, her sons Prince William and Prince Harry visited the floral tributes, and took time to thank the crowds for their well wishes.

On Twitter, Kensington Palace wrote: "The Duke and Prince Harry are grateful for the many flowers, letters and messages they have received about their mother.

"They wanted to say thank you to those who had made the journey to Kensington Palace."

The two brothers and William's wife Kate Middleton also visited the White Garden that has been planted in the palace gardens in memory of their mother - and they hosted representatives from half a dozen charities that she supported in the years before she died.

Peter Waddup from The Leprosy Mission said she continues to have an impact, after becoming the most high profile person in the world to touch anyone who had leprosy.

File photo of Diana, Princess of Wales, touring a minefield in body armour, during a visit to Angola | Image: John Stillwell/PA Wire/PA Images

He said: "There was certainly this opinion this woman that was admired by so many people that she is a bit crazy because she is getting near to people that most of us wouldn't speak to and wouldn't go near and so it was incredible the impact she had.

"We work in 32 different countries, everything she did, all the personal meetings she had with patients affected by leprosy are still making a difference today."

There are no formal events planned to mark her death and Princes William and harry are expected to spend the day privately.

Crowds are expected to gather in Kensington Palace gardens.

Throughout the summer newspapers and magazines have run dozens of articles about every aspect of Diana's life.

Television documentaries have also reflected on the circumstances surrounding her death and her legacy.

Here is how several broadcasters broke the news 20 years ago: