Joint Base Myer–Henderson Hall is a Joint Base of the United States military that is located around Arlington, Virginia which is made up of Fort Myer (Arl), Fort McNair (SW DC), and Henderson Hall. It is the local residue of the Base Realignment and Closure, 2005 process. It is commanded by the United States Army but has resident commands of Army, Navy, & Marines. Most conspicuous is the Arlington National Cemetery Honor Guard.

The two eponymous bases are co-located along the west boundary of the cemetery, and Fort McNair is across the Potomac River, in Washington, DC, on the Anacostia River.

On Fort McNair sits Grant Hall which is the location of the 1865 military tribunal of the conspirators of the Assassination of Abraham Lincoln. Each quarter the Hall is open to the public where people can visit the courtroom and learn more about the trials.