The city of the title has an upper level, “the Club of the Sons,” enhanced by a recreational annex, the Eternal Gardens, where aristocratic youths cavort and improve themselves in hygienic sports and dalliances. On the middle level are the tremendous and demanding machines to whose workings the people from the lower level apply themselves 10 hours a day. The exhausted laborers leave the factory in shifts, through a tunnel leading to elevators that carry 40 persons at a time to their concrete shanties in the lower depths.