Roma XIII was one of many parallel universes where the Roman Empire never fell. Emperor Hieronymous successfully unified the various state-sanctioned religions into one obsessed with death and the afterlife. The inhabitants saw no difference between the living and the dead, living and working among their elaborate tombs and speaking to invisible spirits.
Rome was a great necropolis built on top of a catacomb. Its cemeteries were long narrow streets filled with the wailing of funeral processions. It was fashionable for women to use cosmetics to make their skin pale, their eyes dark, and their hair gray. The world was ruled by Emperor Crolix LI, who led debates among the spirits of his dead predecessors in the Senate.
Despite being relatively close to Roma I, all ambassadors were accepted as spirits and ignored, so the world was dismissed as too superstitious to have anything to teach the Empire of Empires. However, when Regina and Ollacondire visited during the war against the Greater German Reich, they met Consobrinus Patruelis, a member of Partes Paradoxum who came to the world to find inspiration in their methodology for new ways to rebel against the Great Houses. (PROSE: Warlords of Utopia)