The Marine Corps Base Quantico, near Fredericksburg, Virginia, is one of the largest United States Marine Corps bases in the world.

It is the site of the Marine Corps Combat Development Command and HMX-1, the presidential helicopter squadron.

The base is the home of major training institutions for both the Marine Corps and federal law enforcement agencies, including:

• the training academy for the Drug Enforcement Administration,
• the FBI Academy,
• the Marine Officer Candidate School,
• and Marine embassy guard training.

The base also houses the FBI Hostage Rescue Team (HRT); The Basic School (TBS), which Marine officers attend after OCS; Marine Corps University; and the Marine Corps Marathon organization.

A replica of the Marine Corps War Memorial, depicting the flag-raising at Iwo Jima, stands at the entrance to the base. (The original stands at the north end of Arlington National Cemetery.)

Marine Corps Base Quantico and the Potomac River surround the town of Quantico. Access to the town is possible only through the base or from the river.