The planning for Armory Square Hospital began on July 7, 1862. It was located in the old Columbia Armory and in purpose-built wooden barracks. The builders put open covered walkways between the barracks rather than closed corridors in order to improve the ventilation in the sick rooms (MSHWR, Pt. 3, v. 1, p. 935).
Because the hospital was the nearest to the steamboat landing, the bodies of many soldiers who died en route were received there.
On December 17, 1864, the hospital had 1000 beds, of which 630 were occupied. (MSHWR, Pt. 3, v. 1, p. 935).