1941    Ground is broken for the construction of The Pentagon.

1943    The world's largest office building, The Pentagon, is dedicated in Arlington, Virginia.

1965    Norman Morrison, a 31-year-old Quaker, sets himself on fire in front of the river entrance to the Pentagon to protest the use of napalm in the Vietnam war.

1965    Vietnam War: The Pentagon tells U.S. President Lyndon B. Johnson that if planned operations are to succeed, the number of American troops in Vietnam has to be increased from 120,000 to 400,000.

1967    Vietnam War: More than 100,000 war protesters gather in Washington, D.C.. A peaceful rally at the Lincoln Memorial is followed by a march to The Pentagon and clashes with soldiers and United States Marshals protecting the facility. Similar demonstrations occurred simultaneously in Japan and Western Europe.

2001    The September 11 attacks take place in the United States. Airplane hijackings result in the collapse of the World Trade Center in New York City, damage to The Pentagon in Arlington, Virginia, and the crashing of a passenger airliner in Shanksville, Pennsylvania.