It has been twenty years since September 11th, 2001. Twenty years since 2,997 lives were taken. Twenty years since the world was forever changed. It is hard to quantify the suffering that 9/11 caused, and impossible to cure all the pain it continues to cause. However, it is necessary to commemorate this day so that we do not forget this atrocity.

Presidents Biden, Obama, and Bush all attended a memorial at the National September 11th Memorial and Museum with their wives along with Rudy Guiliani, the mayor of New York City during the attacks. The memorial featured five separate moments of silence at 8:46 a.m., 9:03 a.m., 9:37 a.m., 9:59 a.m., and 10:28 a.m. These were the times when American Airlines Flight 11 hit the north tower, United Flight 175 hit the south tower, American Airlines Flight 77 hit the Pentagon, the south tower fell, and the north tower fell, respectively. Bruce Springsteen sang “I’ll See You in My Dreams” and the full names of all the innocent people who perished on that day were also read aloud.

But the occasion wasn’t commemorated only in the U.S. On September 13th, 2001, Queen Elizabeth II ordered the US national anthem to be played during the changing of the guards ceremony at Buckingham Palace. And at Windsor Castle, the anthem was played again in honor of the tragedy as well as the 67 English citizens killed on that day. In a statement released on Twitter, Queen Elizabeth stated that “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.”

At the Pentagon, the Retired Deputy Chief of the Alexandra Fire Department Byron Alexander, mentioned how these memorials are important as “Many of our recruits were either babies or weren’t even born when 9/11 occurred, so they don’t really understand.” Many families who lost members 20 years ago reflected on how they could not believe that much time had passed. Former President George W. Bush also attended a private memorial in Shanksville, Pennsylvania.

Bush addressed the nation, as he did that day 20 years ago. “On America’s day of trial and grief, I saw millions of people instinctively grab for a neighbor’s hand and rally to the cause of one another…That is the America I know.” Bush pointed out how imperative it is to point out the heroism that occurred on this day. This heroism, along with the bloodshed deserves to be remembered.