The most important building on the frontier post, this warehouse held essential food and equipment for the soldiers. These supplies traveled up the Mississippi to the fort each spring, were unloaded at the landing below the fort and hauled up the steep landing road for storage. A winch carried the barrels of supplies to the four floors of the commissary, which, according to Colonel Snelling, could hold four years' worth of supplies.
The east end of the building contained quartermaster goods including clothing, tools and equipment. The larger west end housed barrels of flour, salt pork, vinegar, whiskey and beans to feed the soldiers. The far west end of the top floor was an office for the post quartermaster and commissary officers and their clerks.
The lower floors soon proved too damp for the storage of perishables. They were not reconstructed or furnished when the Minnesota Historical Society rebuilt the Commissary. The original building was demolished in 1895. The site was a major archaeological project prior to reconstruction.
Exact replicas of uniforms, equipment and food storage barrels fill the top floor of the Commissary, and costumed tour guides operate the winch and conduct inventories as they portray store keepers of the 1820s.