Meghan Markle and Prince Harry honored people who passed away on September 11, 2001, by listing the names on their Archewell website.
"IN MEMORIAM. SEPTEMBER 11, 2001," the top of the page says before showing people's names.
That same day, Queen Elizabeth also posted a message about the tragic terrorist attack that occurred in New York and D.C. 20 years ago.
"As we mark the 20th anniversary of the terrible attacks on 11th September 2001, my thoughts and prayers — and those of my family and the entire nation — remain with the victims, survivors and families affected, as well as the first responders and rescue workers called to duty," she said in a statement on Saturday, September 11.
"My visit to the site of the World Trade Center in 2010 is held fast in my memory. It reminds me that as we honour those from many nations, faiths and backgrounds who lost their lives, we also pay tribute to the resilience and determination of the communities who joined together to rebuild," the 95-year-old continued.
"The Queen’s message to the President of the United States on the 20th anniversary of the attacks on 11th September 2001," the caption read.
The Queen's guards at Windsor Castle played "The Star-Spangled Banner" during the Changing of the Guard around 11 a.m. local time, but she wasn't in attendance.
"We're incredibly grateful to the gesture by Her Majesty, the queen," special guest and acting U.S. Ambassador, Philip T. Reeker, said. "The playing of our National Anthem today at the Changing of the Guard represents the friendship, the solidary between our two countries. I think this has shown that the special relationship remains so crucial to all of us."
Camilla, Duchess of Cornwall and Prince Charles also spoke out, writing, "On the 20th anniversary of the 9/11 terrorist attacks, we remember all those who lost their lives and pay tribute to the tireless work of the emergency services, some of whom paid the ultimate sacrifice to save others."