It has been 20 years since the September 11 attacks.
Across the country, people are pausing to honor the victims and reflect on the day.
Nearly 3,000 people were killed when hijackers crashed planes into the World Trade Center, the Pentagon and a field in Pennsylvania.
"These memorials are really important," said President Joe Biden, who visited all three sites. "But they're also incredibly difficult for the people affected by them, because it brings back the moment they got the phone call. It brings back the instant they got the news, no matter how years go by."