This Thursday (Sep 11, 2025) marks 24 years since Al Qaeda operatives carried out the deadliest terror attacks on America in the country’s history, killing nearly 3,000 people and injuring thousands more. These 20 documentaries — selected from more than two decades of extensive FRONTLINE reporting — probe that fateful day, investigate the cascade of decisions that followed and trace the lasting impact on the U.S. and the world.