Named after Rear Admiral John A. Dahlgren, an influential figure in the development of naval ordnance.  Its large, open space was ideal for indoor drills and military exercises. The hall was constructed between 1899 and 1903. Its design was overseen by Ernest Flagg, a prominent architect who designed several buildings at the Naval Academy. Today it houses the Drydock Restaurant, a gathering place for midshipmen, faculty, and visitors.