Charles Spencer has honoured his late sister, Princess Diana, on the 28th anniversary of her death by leaving flowers at her burial site.

In a touching Instagram post shared on August 31, the 61-year-old 9th Earl Spencer posted a photo of a bouquet he personally gathered from the grounds of Althorp Estate, Princess Diana’s final resting place.

Charles Spencer pays tribute to Princess Diana on the anniversary of her death

“Flowers we cut this morning from Althorp’s gardens for the Island,” he wrote in the caption, referring to the secluded island on Oval Lake where the former Princess of Wales is buried . “Always an impossible day.”

The image featured white and pink roses placed in tribute to Diana. A second photo showed the quiet, tree-lined island on the estate, nestled in the gardens of Althorp in Northamptonshire.

In a follow-up post, Charles shared an image of floral tributes left by visitors at the public memorial on the Althorp grounds.

Flowers we cut this morning from Althorp’s gardens for the Island.

“Beautiful flowers, left yesterday by Althorp’s visitors,” he wrote. “We are open for July and August each year, by an arrangement reached with the UK Government in 1992. Strange to think that that summer season is bookended by 1 July – Diana’s birthday – and 31 August – the day she died.”

He also thanked the Althorp House team for their service during the visiting season: “My deepest thanks go to the @althorphouse team, who were truly outstanding again this summer.”

Meanwhile, fans and followers flooded the comment section with heartfelt messages.

“She will live in our hearts forever,” one wrote.

Another gushed: “Diana will never be forgotten. She really was the people’s princess.”

“Thank you for keeping her memory alive and allowing visitors to pay tribute,” a third also commented.

One follower added: “You could have kept her burial site private but you recognise how popular and loved she is and allow the public to visit. Thank you.”

Where is Princess Diana’s burial site?

Princess Diana was tragically killed in a car crash in Paris on August 31, 1997, alongside Dodi Fayed and their driver Henri Paul.

Her death shocked the world and left her two young sons, Prince William and Prince Harry, without their mother.

Following her death, Charles Spencer chose to lay his sister to rest on a small island within Althorp’s Oval Lake, a space that would offer privacy and serenity for both her family and visitors.

Speaking to PEOPLE previously, Charles said: “I think it’s very important for [William and Harry] to be there with her. It is, luckily, very tranquil here and they can come and go as they wish whenever they want. And that’s very lovely for me to know that.”

In his 1998 memoir Althorp: The Story of an English House, he wrote: “We all agreed that, with its beauty and tranquility, this was the place for Diana to be.”

The grave itself is off-limits to the public. However, Althorp Estate remains open for part of the year. However, visitors are able to pay tribute at a designated memorial on the grounds.