Monday marks the 23rd anniversary of the death of Princess Diana, who was killed in a car crash in Paris, France on August 31, 1997 at the age of just 36. To mark the solemn occasion, Diana’s brother Charles Spencer took to social media to pay a touching tribute to her.

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

My first family duty on 31 August. Never forgotten. pic.twitter.com/onDcMikvqw

— Charles Spencer (@cspencer1508) August 31, 2020

PEOPLE magazine reported that Diana grew up at Althorp House in Northamptonshire, England, which has been in her family for over 500 years. Spencer currently lives there with his family, and it is also the location of Diana’s grave.

Back in 2017, Spencer opened up about his sister, saying that the media’s nickname of her as “Shy Di’ could not have been more inaccurate.

“First of all, none of us ever called her ‘Di’ at home,” Spencer said. “In fact, there are so many myths from our childhood that are just so ridiculous. That’s one of them. I just think she was never shy, but she was canny about people and she was reserved to start with. And she would take a judgment of somebody before reacting to them. So, that’s not shy . . . that’s actually quite clever.”

Spencer also said that Diana was an “incredibly brave” girl, recalling one childhood story in which the young siblings were staying with their mother in Scotland and set out to catch lobsters.

“We pulled up [a pot] and there was a really massive conger eel,” he told PEOPLE. “It was black and it had teeth was very long and it was flapping around the boat. And Diana just got a pen knife out and just dealt with it. It was hand-to-hand and she just got stuck in. This thing was really a creature from the deep. And she just dealt with it.”

Spencer remembers Diana as someone who had “a genius for people and she could connect with anyone.”

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

Though it’s been 23 years since her passing, Diana continues to be missed by millions of people all over the globe.