Explanation

Ground Zero is the site where the World Trade Center's Twin Towers stood in New York City before they were destroyed in the terrorist attacks on September 11, 2001.

September 11 attacks, also called 9/11 attacks,

Series of airline hijackings and suicide attacks committed in 2001 by 19 militants associated with the Islamic extremist group al-Qaeda

against targets in the United States, the deadliest terrorist attacks on American soil in U.S. history.