The Hagerstown Armory, erected in 1926, is a two-story structure with full basement emulating a Medieval fortification. The structure is brick, with the front block executed in Flemish bond. Attached to the rear of this 2-story main block is a narrower 1-story drill hall. A modern 1-story garage has been added to the rear of the drill hall. The front (Potomac Street) façade is oriented to the west, and consists of two, two-bay wide sections which flank a central block offset by two, three-story towers. In the side sections, windows at first floor level are 4/5 casement with bases set into the stone water table. At second floor level are 4/4 casement windows. All windows have stone sill and flat brick lintels. A line of scalloped stone molding crosses the side sections above the second floor windows. At the roofline six crenelles with stone caps crown each section. The towers which mark the front entrance to the building are octagonal, with one window in each of their three full sides, 2/5 casement at first and 2/4 casement at second floor levels. Window arches and sills correspond to those of the side sections with the addition of triangular white end stones in the arches. Centered above the second floor windows, in a line corresponding to the scalloped stone molding of the side sections, three square stone panels are set into the tower walls. At the third floor level single 1/1 sash windows are centered in the tower walls with bases set into a stone molding running around the towers. Tower tops are characterized by a ring of scalloped stone molding, surmounted by a ring of brick dentils, and topped by two crenelles per side with stone caps. At center front, three cement steps lead to a segmentally arched entry under which painted metal double doors are recessed 2-3 feet. A stone panel over the arch is inscribed "Maryland National Guard." At second floor level is a 6/4 casement window with stone sill and flat brick arch bracketed with white stones at its corners. A band of scalloped stone trim corresponding to that of the side sections crosses above the window. At the roofline, the stone molding corresponding to the third floor of the towers crosses the center section. The center is topped by two crenelles with stone caps with stone tablet bearing the seal of the State of Maryland centered between them.
The Hagerstown Armory is primarily significant for its association with the reorganization and expansion of the National Guard system in the 20th century. It derives additional significance from its role as a social center for its community, a function it has served continuously since its construction date. Architecturally, the building embodies the distinctive characteristics of its type, including a T-shaped plan with a two-story front "head house" section and a one-story perpendicular "drill hall" extending to the rear; its façade is detailed to recall Medieval fortifications, with towers flanking the central entrance, crenellated parapets, and strip buttresses
The armory sat mostly vacant for decades after the National Guard vacated the building in 1978. The building was finally purchased in 2009 and has now been converted to private mental health center. The building appears to be in very good condition.