This book provides a rigorous historical and socio-religious analysis of the cult of Cybele (Magna Mater) and her paredros Attis in ancient Rome. Originating as a revised study by Alessandro Giuli, the work examines the ritual, political, and mythical dimensions of the deity's integration into the Roman pantheon following her transfer from Phrygia in 205 BCE. Utilizing a rich array of classical literary sources, epigraphic data, and modern historiographical frameworks, the text explores the tension between eastern ecstatic practices and traditional Roman religious orthopraxy, overseen by the patrician elite. Key chapters investigate the public rituals—such as the Megalesia and the taurobolium—alongside the mythistorical narratives that bound the Great Mother to Trojan origins and the divine destiny of Rome (Aeternitas Romae). Ultimately, the volume illuminates how the Roman state adapted foreign sacred traditions to reinforce aristocratic identity, civil cohesion, and imperial ideology throughout the Mediterranean world.