The sons of Princess Diana are honoring her on what would have been her 56th birthday!

The royal brothers, Prince William and Prince Harry along with family gathered on Saturday to pay tribute to their beloved mother, who died in a car crash in Paris, France, on Aug. 31, 1997.

The royals rededicated her grave and held a private memorial service on the island of the Oval Lake at Althorp House in England, the Princess of Wales’ family estate in Northamptonshire where she grew up and was laid to rest nearly 20 years ago.

Prince William and wife, Kate Middleton, was present along with their two children, Prince George, 3, and Princess Charlotte, 2, and Diana’s brother, Charles Spencer, 9th Earl Spencer. However, Prince Charles — Diana’s ex-husband and Harry and William’s father — was notably absent from the service, as he was performing Royal duties in Ottawa with his wife, Camilla, Duchess of Cornwall, in honor of Canada’s 150th birthday, The Telegraph reports.