"Dateline" is airing a new episode about 9/11. Here's everything you need to know to watch, live or later on, if you missed it.

Anchored by Lester Holt, the one-hour documentary features never-before-seen NBC News archive footage from Sept. 11, 2001.

Footage captures Zohran Mamdani greeting Rudolph Giuliani at Ground Zero as victims' families and first responders criticize his 9/11 attendance.

Western Mass News spoke with a retired fire department lieutenant who helped in the search and rescue

Photographer Thomas E. Franklin took one of the most famous photos from 9/11, firefighters raising an American flag from the rubble of Ground Zero.

After 9/11, thousands of rescue and cleanup crews went to work at ground zero. They were exposed to toxic debris and experienced psychological trauma. Today, many say they live in fear of deportation.

Friday marks the 25th anniversary of the September 11 terror attacks — and once again the National September 11 Memorial & Museum will honor the 2,977 people who were killed in the tragedy with its annual commemoration ceremony.

A retired NYPD officer who responded to Ground Zero was diagnosed with a form of cancer that's being linked to toxic exposure.

Retired Clarksville dentist Dr. Ernie DeWald reflects on volunteering at Ground Zero after the Sept. 11 attacks, helping with victim identification efforts and supporting families.

The South Tower dissolved at 9:59 a.m. Bloodied survivors were already emerging on the street from a spew of dust and ash. Overhead, the North Tower torched the sky. Smoke and flames churned out of a six-floor gash near the top.