After the terrorist attacks on Sept. 11, 2001, the nation rallied under the cry “Never forget.”

But 25 years later, several lessons that emerged from that day of death and destruction have been forgotten, according to a panel of experts at a John F. Kennedy Jr. Forum at the Institute of Politics on Tuesday night.

Three panelists — the first New York Fire Department chief to respond to the attack, a Navy admiral who was in the Pentagon that day, and a journalist who covered it for Time magazine — were all personally impacted by the attack.

Chief of Counterterrorism and Emergency Preparedness for the Fire Department of New York, Joseph Pfeifer, now a Kennedy School senior fellow and author of “Ordinary Heroes: A Memoir of 9/11,” was inspecting a suspected gas leak nearby in lower Manhattan at 8:46 that morning when the first plane hit the North Tower of the World Trade Center.

“Every first responder looked at the burning building and knew they were going to the most dangerous fire of their lives,” he recalled.