Lithographed images of hospitals were used on stationary provided for convalescing soldiers during the Civil War. In the case of both the Armory Hospital and the Columbia College and Carver Barracks Hospitals in Washington, D.C., more than one version was published, as the number after the titles indicates. The bird's-eye views show the unit-and-pavilion system on which American military hospital architecture of the 1860s was based; the advantage of such a system was that a number of small buildings could be constructed quickly to meet emergency needs. William H. Helfand, from The Picture of Health: Images of Medicine and Pharmacy from the William H. Helfand Collection (1991), p. 129.