The Walter Reed Army Institute of Research (WRAIR) is the largest biomedical research facility administered by the U.S. Department of Defense. The institute is centered at the Forest Glen Annex, part of the unincorporated Silver Spring urban area in Maryland just north of Washington, DC, but it is a subordinate unit of the U.S. Army Medical Research and Materiel Command (USAMRMC), headquartered at nearby Fort Detrick, Maryland. At Forest Glen, the WRAIR has shared a large, modern laboratory and administrative facility — the Sen Daniel K. Inouye Building, also known as Building 503 — with the Naval Medical Research Center since 1999.