The Chicago and North Western Railroad had a massive full circle roundhouse at their Proviso Yard in Chicago, Illinois. Jack Delano visited the facility in December of 1942 and captured this image, along with several others inside the structure. This aerial view shows how large a building such as this is. It obviously takes a mammoth amount of water to quench the thirst of the dozens of locomotives that see this facility each day as evidenced by the presence of three massive steel water tanks in the background.
Despite the heat generated by some of the locomotives under fire while in the building, it was still drafty in the dead of winter. I posted this image a while back of a coal-fed fire burning inside the roundhouse to give a bit of warmth to the workers.