The National Register's Registration Form provides a fairly lengthy description:
The Milam Store Building is among the oldest buildings in Glen Rose, as is the adjacent Corner Drug Store (Property #33). Both date from the early 1880s, with family traditions in the Milam family stating that the mercantile business began in 1881, with the first stage of a phased construction coming about this time. The limestone One-part Commercial Block originally with nine bays measures 76 feet long, 79 feet 1 inch deep at the southwest end and 80 feet 1 inch deep at the northeast end. It has a flat roof that gently slopes to the rear for drainage through metal gutters to a central metal downspout. The surviving masonry portion of the Milam Store Building was constructed in two phases. The first consists of the northeastern end that measures 30 feet 5 inches across, while the later southwestern end measures 45 feet 7 inches across. The front of the first phase had four bays, each fitted with a pair of doors with one-over-one fixed glass windows. These doors opened directly onto a wooden sidewalk. Above these doors were two-part fixed glass transoms, while the otherwise plain cornice was decorated with pressed metal ornamentation. The older building shared a wall with the adjacent Corner Drug Store (Property #33). When the second phase of the matching limestone building was added, it shared one wall with the preexisting store and was constructed southwestward to the edge of a natural drainage channel known as the Connell Branch, its southwest wall extending downward into the sloping side of the Connell Branch streambed. The addition had five more bays. At the time of the expansion, the front of the entire building was made uniform in appearance. The front openings were modified by enclosing six of the bays with fixed glass display windows while three of the double door openings were retained. Two-pane glass transoms topped both doorways and display windows. The pressed metal cornice on the older portion of the building was removed and the entire front given unity through addition of a single-course of slightly protruding stone. At the center a rectangular extension of the cornice with embellishments provided decoration. At some date after 1925 a wooden awning with metal roof supported by iron rods was placed across the front of the building to shelter customers on the sidewalk.
The rear of the Milam Building has two entry doors. One entry serves the older northeast portion of the building. It is fitted with double doors, each having twelve fixed panes of glass. Above this rear entry is a small canopy and two two-pane transoms. On either side of this rear entry is one window, one boarded up and the other closed with historic steel shutters. Another rear entry with five steps is located near the center of the rear wall in the newer southwest end of the structure. It gives the appearance of having once had a double-door entry, but the opening has been boarded in and fitted with a single windowless door. Tall window openings on either side of this second rear door have been filled in and covered with a stucco-like material. The southwest side of the building, facing Connell Branch, has one doorway opening at interior floor level located toward the rear that has been closed using historic steel shutters.
In the mid-1920s a now-lost galvanized-corrugated-sheet-steel-covered wood-frame addition to the Milam Store was constructed at the southwest end of the store. The barn-like structure stood on vertical wooden timbers above the intermittent waters of the Connell Branch and served initially to house and display wheeled vehicles sold by the firm. This lightly-built steel-clad wood-frame structure survived into the 1950s, after which time it ceased to appear in historic photographs.
The front of the southwest end of the Milam Store Building was modified considerably in 1962 in order to accommodate the sales needs of a commercial tenant. Vertical steel posts replaced two of the stone supports; this allowed three large fixed plate glass windows resting on 1-foot 4-inch-tall narrow pinkish-grey brick pedestals to flank a large single glass entry door with fixed glass sidelights, all framed in aluminum. Above the display windows, sidelights, and single entry door were additional rectangular fixed plate glass panes likewise framed in aluminum. A metal awning suspended on iron rods was retained, but the facade above the windows was sheathed using an aluminum and pale yellow fiberglass slipcover. At this time the central stone ornamentation atop the center of the cornice was removed, and some of its cut limestone blocks reused to form the base for the Veterans' Memorial (property #6) on the courthouse square. The historic structure presents the same appearance that it has since 1962.
Members of the Milam family operated a mercantile building in the Milam Store Building from the early 1880s until 1960. J.R. Milam founded the enterprise, and it incorporated in 1905. C.A. Milam succeeded his father as principal in the firm and operated it until its closing. One of the large general mercantile businesses in the town, the store sold a wide range of goods including groceries, dry goods, wheeled vehicles, harness, agricultural tools and equipment, and caskets. C.A. Milam also became owner of a considerable amount of agricultural land in the area, usually receiving a portion of the crops raised as his rent payment. Frequently he extended credit to his tenants in the form of merchandise from the store. After the death of C.A. Milam in 1955, his son, C.A. Milam, Jr., succeeded him until selling the business five years later.
After the Milam Store sold its stock and closed in 1960, a series of enterprises operated in the building. Generally one renter occupied the original thirty-foot-wide original structure with another occupying the slightly newer 46-foot-wide end. For several years Mr. Jerre Deason operated a store there selling appliances, tires, household items, and sporting goods that was franchised to the White Auto retail chain. Deason's business began in the older end of the store, but then in 1962 property owner Maggie Snyder remodeled the larger end to accommodate her tenant's growing trade. The local press reported approvingly, "The front of the building is aluminum with plenty of plate glass for lighting and appearance." By 1965 the older part of the building adjacent to the White Auto Store had been occupied by the Thrift Center secondhand store operated by volunteers from the First Methodist Church. Currently the retail space at the older northeast end of the building is vacant, while the Spirit Wind Church has occupied the newer southwest end since the 1990s. The drainage channel for Connell Branch, over which a lightly-built sheet-metal-covered frame addition to the store once stood, in recent years has been landscaped with plants that naturally produce food for birds.