The Boscobel Grand Army of the Republic (G.A.R.) Hall is located in a residential neighborhood south of the City of Boscobel's central business district. The building is finished with broad clapboards, trimmed with simple cornice and corner boards, and rests on a fieldstone foundation. Erected as the First Baptist Church in 1871, it was significantly remodeled in 1896 to serve as the meeting hall for the John McDermott Post #101, G.A.R., and its ladies' auxiliary, the John McDermott Woman's Relief Corps (W.R.C.) #32. The 1896 remodeling installed the existing windows and a front porch, and divided the interior into two floors, with two rooms and a kitchen on the first floor, and a large meeting hall on the second floor. Many furnishings original to the 1896 remodeling remain in place, including three cast iron stoves, a long dry sink in the kitchen, tables, chairs, and other items used by the G.A.R. members. The meeting hall also contains several plain wooden pews and an organ, used by the G.A.R. members, but acquired from the First Baptist Church.

The Boscobel G.A.R. Hall is one of only two, intact buildings known to have been owned by and dedicated to the G.A.R. The John McDermott Post #101 of the G.A.R. occupied the building from 1896 until the death of its last member in 1942. The John McDermott W.R.C. #32 has met in the building since 1896, and continues to carry out one of its original missions, the perpetuation of the memory of Union veterans, through caring for the building and its Civil War artifacts.

In 1989, the Woman's Relief Corps organized the Boscobel Grand Army of the Republic Hall Preservationists, Inc. (B.G.A.R.H.P.), transferring the building to the B.G.A.R.H.P. in 1990. The Boscobel G.A.R. Hall is currently operated as a museum, open to the public on Saturday afternoons during the summer, or by special appointment. It houses a collection of artifacts, records and memorabilia from the Civil War, as well as the G.A.R., the W.R.C., and the Sons of Union Veterans of the Civil War.