The State School root cellar stored vegetables grown in the large garden for consumption by children and staff, along with canned vegetables and the school's large apple crop. Its north half was constructed in 1898 with inside walls and arched ceilings lined in cut fieldstone, balanced and supported with small wooden shims, and a self-supporting ceiling without beams over concrete floor squares. The south half was added in 1922 at a cost of $3,600, with more simply built walls and ceiling and an all poured concrete floor. Each half is approximately 11 feet high, 58 feet long, and 16 feet wide, with three feet of soil and grass covering the top and an inside temperature that remained near 42 degrees year-round, though a kerosene heater was used during extremely long cold spells to prevent freezing. Bins and pull-out drawers along the walls separated carrots, onions, turnips, beets, pumpkins, squash, and potatoes, which were unloaded through outside trapdoors into bins below, while daily checks guarded against spoilage. In the 1930s-40s, the cellar's food helped feed a nearly constant population of 400-500 children and 100 staff three meals a day, seven days a week. After the City of Owatonna purchased the property from the State of Minnesota in 1974, the cellar was used for a time each spring to store bare root trees for planting, then had its cement front refaced and doors replaced in 2002, and its interior upgraded for group tours in 2014.