United States Department of Defense

Department of Defense
Learn about the Department of Defense and The Pentagon building

Overview of the United States Department of Defense

The United States Department of Defense (DOD or sometimes listed as DoD) is the federal department responsible for coordinating and supervising all agencies and functions of the government relating directly to national security and the military. The organization and functions of the Department of Defense are outlined in Title 10 of the United States Code.

The Department of Defense is the primary tenant of The Pentagon building near Washington, D.C., and has three major components: The Department of the Army, The Department of the Navy, and the Department of the Air Force.

To learn more, visit the official Department of Defense website. The website includes the latest news and issues the department is dealing with. Provides a list of all DOD sites and other resources.

Among the many Department of Defense agencies are:

  • The Missile Defense Agency
  • The Defense Advanced Research Projects Agency (DARPA)
  • The Pentagon Force Protection Agency (PFPA)
  • The Defense Intelligence Agency (DIA)
  • The National Geospatial-Intelligence Agency (NGA)
  • The National Security Agency (NSA)

Training Academies

The department also operates several joint service schools and training academies, including the National War College. Following are military training academies sponsored by the DOD:

  • Air Force Academy (Colorado Springs, Colorado)
  • Coast Guard Academy (New London, Connecticut)
  • Merchant Marine Academy (Kings Point, N.Y.)
  • Military Academy (West Point, N.Y.) – Provides education and training for the U.S. Army.
  • Naval Academy (Annapolis, Maryland) – The undergraduate college of the United States Navy that trains men and women to become professional Navy officers.

The Pentagon: The United States Department of Defense Headquarters

The Pentagon is the headquarters of the United States Department of Defense and is located in Arlington, Virginia. “The Pentagon” is often used to refer to the Department of Defense rather than the building itself.

The Pentagon was designed by the American architect George Bergstrom (1876 – 1955).  The Pentagon was built by Philadelphia, Pennsylvania, general contractor John McShain.  The Pentagon building was dedicated on January 15, 1943, after the ground was broken for construction on September 11, 1941.

The Pentagon Reservation

The Pentagon Reservation is located in southeastern Arlington County, Virginia. It is situated between a large man-made lagoon (the Pentagon Lagoon, formed during construction) and the southeastern corner of Arlington National Cemetery. The northeastern and eastern facades have unobstructed vistas of the Monumental Core of the Nation’s Capital across the Potomac River.

The Pentagon’s relatively low profile also permits clear vistas of Washington from the highlands of Arlington National Cemetery. The Pentagon is the world’s largest office building by floor area, with about 6,500,000 square feet, of which 3,700,000 square feet are used as offices. The Pentagon building is twice the size of the Merchandise Mart in Chicago, Illinois, and has three times the floor space of the Empire State Building in New York.

The U.S. National Capitol could fit into any one of the five wedge-shaped sections. Approximately 23,000 military and civilian employees and about 3,000 non-defense support personnel work in the Pentagon.  The Pentagon has five sides, five floors above ground (plus two basement levels below ground), and five ring corridors per floor with 17.5 miles of corridors.

The building includes a five-acre central plaza, which is shaped like a pentagon and informally known as “ground zero,” a nickname originating during the Cold War and based on the presumption that the Soviet Union would target one or more nuclear missiles at this central location in the outbreak of a nuclear war.

The Pentagon Official Website – Provides information on the Pentagon, the history of the Pentagon, Pentagon tour booking information, facts and figures, and more.

Learn about other government intelligence agencies.

Michael Kissiah is the owner of Brandy Lane Publishing, LLC, which owns and operates a small portfolio of websites, including eInvestigator.com. Michael created eInvestigator.com more than 20 years ago after working as a private investigator in the state of Florida. Since that time, he has become an expert at how to find information online and has written over 1000 articles on topics related to the investigation industry. In addition, he is the author of the "Private Investigator Licensing Handbook", available at Amazon.com.


  1. I cannot find an email address for the Sec. of Defense, James Mattis. I have a question for him. Yesterday, President Trump said the US would soon withdraw troops from Syria. At present, there are at least 2000 occupying space in Syria along with SDF troops funded by the US. Their spokesperson followed up the Trump statement saying they have no word of the proposed change. Who is lying, Truimp or the SDF spokesperson? Secy. Mattis can kindly answer that, Or, does his silence mean that he doesn’t know who is the liar. To me, a US citizen and Korean War vet it seems that there is still a US goal of regime change in Syria. If so, why?


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