Below are some military units. DC also hosts many national government agencies related to this industry (you can also wander around and particularily in VA).
Fort Myer, DC Fort Myer Military Community - FMMC - Fort Myer Washington army.mil fmmc.army.mil
Washington Navy Yard, DC MSC - US Navy Military Sealift Command navy.mil msc.navy.mil
Washington Navy Yard, DC United Service Organizations, Inc. - UWH - USO World Headquarters org uso.org
Washington, DC AFIS - American Forces Information Service osd.mil afis.osd.mil
Washington, DC Joint Force Headquarters National Capital Region - JFHQ-NCR, USNORTHCOM mil jfhqncr.northcom.mil / ws9.jfhqncr.northcom.mil
Washington, DC Lisa R. Hilliard, Naval Research Laboratory navy.mil lhilliard.nrl.navy.mil
Washington, DC MRMS - US Navy's Maintenance Resource Management System navy.mil mrms.navy.mil
Washington, DC National Defence University edu ndu.edu
Washington, DC Navy Medicine - Bureau of Medicine and Surgery navy.mil navymedicine.med.navy.mil
Washington, DC Office of the Assistant Secretary of Defense for Public Affairs - OSD-PA osd.mil osd.mil
Washington, DC Stars and Stripes osd.mil stripes.osd.mil / stripes.com / cssgw-uu.stripes.osd.mil…
Washington, DC United States Coast Guard - USCG mil uscg.mil / gateway-**-*.uscg.mil / gateway-**-**.uscg.mil…
Washington, DC US Naval Research Laboratory - NRL navy.mil nrl.navy.mil
Washington, DC US Navy Bureau of Medicine and Surgery navy.mil med.navy.mil
Washington, DC USACE - U.S. Army Corps of Engineers army.mil usace.army.mil
Washington, DC USMC MCCS - United States Marine Corps Marine Corps Community Services org usmc-mccs.org
Washington, DC Washington Headquarters Services - WHS - The Pentagon mil whs.mil / wakko.whs.mil
See all lists of US military visitors.