'The Never Ending Factory of the Duomo' tells the story of the ongoing construction, preservation and maintenance of the Milan Cathedral over six centuries. The film sheds light on the painstaking labour of caring for a public monument through delicate imagery of the inner workings of the cathedral. The viewer sees several types of work carried out: the quarrying of Candoglia marble earmarked as building material, the management of the cathedral's historical archives, the maintenance of the statuary yard, the reproduction of architectural features, and the preservation of the Madonnina spire atop the cathedral.