Heroism took many forms on September 11, 2001—in burning offices, aboard hijacked planes and amid the choking dust of the pile. To honor that legacy, we asked 9/11 experts for their top book recommendations. These five powerful titles illuminate different dimensions of courage under the day’s unimaginable pressures, from firefighters’ final stands to plane passengers’ defiant resistance. Together, they ensure that the day’s sacrifices and resilience are never forgotten.