Helena by Evelyn Waugh

The Empress Helena, mother of Constantine the Great, made the historic pilgrimage to Palestine, found pieces of wood from the true Cross, and built churches at Bethlehem and Olivet. Her life coincided with one of the great turning-points of history: the recognition of Christianity as the religion of the Roman Empire. The enormous conflicting forces of the age, and the corruption, treachery, and madness of Imperial Rome combine to give Evelyn Waugh the theme for one of his most arresting and memorable novels.