This thesis explores the last decades of legal paganism in the Roman Empire of the second half of the fourth century CE through the eyes of Symmachus, orator, senator and one of the most prominent of the pagans of this period living in Rome. It is a religious biography of Symmachus himself, but it also considers him as a representative of the group of aristocratic pagans who still adhered to the traditional cults of Rome at a time when the influence of Christianity was becoming ever stronger, the court was firmly Christian and the aristocracy was converting in increasingly greater numbers. Symmachus, though long known as a representative of this group, has only very recently been investigated thoroughly. Traditionally he was regarded as a follower of the ancient cults only for show rather than because of genuine religious beliefs. I challenge this view and attempt in the thesis to establish what were his religious feelings. Symmachus has left us a tremendous primary resource of over nine hundred of his personal and official letters, most of which have never been translated into English. These letters are the core material for my work. I have translated into English some of his letters for the first time. The thesis is organised in the main thematically, looking at Symmachus’ religious language, pagan religious ritual, the changing religious topography of Rome itself – and the clash with the Christian establishment specifically with Bishop Ambrose of Milan over the Altar of Victory Affair. The last chapter, although still thematic, looks at Late Antique Paganism through a series of personal events in Symmachus’ life; but is also chronological in the sense that it covers the last seventeen years of it. There are six appendixes, tables and illustrations.