Rodolfo Lanciani writes about the monumental transformation of ancient Rome from a pagan city into a Christian center, examining how classical structures, traditions, and municipal institutions were absorbed, modified, or replaced by the early Church. The book poses the historical problem of how early Christians navigated public and official life in a pagan society, detailing the conversion of Roman patrician families, such as the Acilii Glabriones and the Flavians, who practised their faith at great personal peril.
The argument develops through a careful analysis of monumental evidence, contrasting literary records with physical remains discovered in the catacombs and beneath modern streets. Lanciani examines the architectural evolution of private houses into early oratories, the conversion of pagan temples into Christian churches, and the preservation of classical art within sacred edifices. He details how ancient customs, such as funerary banquets, rose-festivals, and public granaries, found new life under Christian administration.
Key chapters cover the transformation of pagan shrines into street-crosses and madonna niches, the history of imperial and papal tombs, and the architectural history of the great basilicas of Saint Peter and Saint Paul. Lanciani details the layout of the ancient city, the discovery of ancient boundary stones, weights and measures, and the favissæ of ancient sanctuaries. He pays particular attention to the Arch of Constantine and the precise location of the tombs of the apostles.
The author avoids mechanical retellings by providing concrete details from source texts and epigraphic discoveries, naming terms and locations precisely as ancient writers and modern excavations reveal them. The narrative gently hints at the gradual, imperceptible nature of this historical transition, showing it to be the natural result of moral superiority and three centuries of quiet growth rather than sudden revolution.
