The Cartographic Branch holds thousands of drawings, plans, and maps relating to forts, fortifications, and other military structures. These can be found in a variety of record groups and series, including RG 77 Fortification Map File (NAID 305749), RG 77 Miscellaneous Forts File (NAID 305806), RG 92 Post and Reservation Maps (NAID 305818), RG 92 … Continue reading Civil War Defenses of Washington Fort Plans Now Available Online