Princess Diana's Brother Charles Spencer Shares Touching Tribute on Anniversary of Her Death

Amanda Edwards/WireImage; Tim Graham Photo Library/Getty Charles Spencer and Princess Diana

Charles Spencer is honoring his sister Princess Diana on the 23rd anniversary of her death on Monday by sharing a glimpse at one of the ways his family marks the poignant day.

“My first family duty on 31 August. Never forgotten,” Charles, 9th Earl Spencer tweeted alongside a photo of the Spencer family flag at half-mast on Monday at Althorp.

Princess Diana grew up at Althorp House in Northamptonshire, England. The stately home has been in her family for more than 500 years and is currently the home of her brother and his family. It is also the site of the late princess’s grave.

RELATED: Charles Spencer Says His Sister Princess Diana Would Have Been the ‘Best Grandmother Ever’

Diana, who died in a car crash in Paris on August 31, 1997, was beloved around the world and stands as one of the key figures of the 20th century.

She had “a genius for people and she could connect with anyone,” Spencer told PEOPLE in 2017— and that was never more apparent than through the way she broke down barriers on AIDS and HIV, tackled the terror of landmines and highlighted the plight of the homeless.

Central Press/Getty Princess Diana and her brother Charles Spencer as children

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“She could make any person, whether they were the grandest or the most humble, totally at ease,” he added. “It’s an incredible gift.”