Volume I of Hartmann Grisar’s History of Rome and the Popes in the Middle Ages provides a scholarly, detailed account of the transition from late antiquity to the early medieval period. It focuses on the city of Rome, the rise of Papal authority, and the church's struggle against Paganism and Arianism at the end of the fourth century. Grisar combines the history of the city itself with the history of the Papacy to create a comprehensive picture of Rome in the Middle Ages. The work is noted for its rigorous research into the early years of the papacy and its influence on the formation of European.