Garrett M. Graff examines the legacy of the 9/11 terrorist attacks.

Historian Garrett M. Graff, author of the New York Times bestseller "The Only Plane in the Sky: An Oral History of 9/11," looks at how our nation remembers the events of September 11th, 2001, how a new generation faces the legacy of events (and wars) older than they are, and how we are still challenged by events that are two decades removed.