The Forest Glen Annex campus includes the 27-acre (110,000 m2) National Park Seminary Historic District which is being redeveloped separately from the military area.
The land on which the Forest Glen Annex now stands was originally part of a huge tract belonging to the influential Carroll family of colonial times, which lived nearby.
In July 1864, Ray allowed the troops of Confederate General Jubal Early to encamp on his land, before sallying down nearby Brookville Road for an unsuccessful raid on Washington, D.C., which ended in the Battle of Fort Stevens.
With U.S. involvement in World War II, the Army's Walter Reed General Hospital needed more space for the convalescence and rehabilitation of returning veterans.
[1] In 2011, in accordance with the most recent Base Realignment and Closure (BRAC) recommendations, the Forest Glen Annex became home to the National Museum of Health and Medicine (NMHM) as well as a "Joint Center of Excellence in Infectious Disease Research."