World leaders are expressing their sympathies for the victims of the 9/11 attacks. British Prime Minister Boris Johnson says the terrorists had failed to "shake our belief in freedom and democracy."

On the 20th anniversary of the 9/11 attacks, the nation paused to remember. Ceremonies took place at memorials in New York City; in Shanksville, Pa.; and at the Pentagon.

There is a long list of ways America was transformed by the terrorist attacks. But the question of how TV itself was changed — particularly in ways still relevant today — is more complicated.

After the attacks, barriers and thigh-high cement bollards sprouted up seemingly overnight in Washington, D.C. But new threats show the need for adaptability.

At least 67 undocumented immigrants, mainly from Mexico and South America, who worked at the World Trade Center on Sept. 11, are still considered missing.

President Biden called on Americans to embrace unity as they reflect on the day that two decades ago reshaped the nation. "Unity is what makes us who we are: America at its best," he said.

No boarding pass or ID was needed to go to the gate, and 4-inch-blade knives were allowed aboard planes. Now we take off shoes, can't have liquids over 3.4 oz and go through high-tech body scanners.

Students today have no memory of the attacks of Sept. 11, 2001, so this year's anniversary poses unique challenges for educators and caregivers trying to explain what happened and why.

While America was under attack on 9/11, Cincinnati voters were holding their first mayoral primary. "It was the oddest day of my career in politics," said then-mayor Charlie Luken.

An 8th grader at the time of terror attacks and her father remember how they felt as members of a minority group living in the U.S.