The dream Alexander the Great and Julius Caesar shared of uniting Europe, the Mediterranean, and the Middle East in a single community shuddered and then collapsed in the wars and disasters of the sixth century. It was a looking-glass world, where some Romans idealized the Persian emperor while barbarian kings in Italy and France worked tirelessly to save the pieces of the Roman dream they had inherited. At the center of the old Roman Empire, in his vast and pompous Constantinople palace, the emperor Justinian, with too little education and too much religion, set out to restore his empire to its glories. Step by step, the things he did to bring back the past sealed the doom of his entire civilization. Historian and classicist James J. O'Donnell—who last brought us his masterful, disturbing, and revelatory biography of Saint Augustine—revisits this old story in a fresh way, bringing home its sometimes painful relevance to issues of our own time. With unexpected detail and in his hauntingly vivid style, O'Donnell begins at a time of apparent Roman revival and brings us to the moment of imminent collapse that just preceded the rise of Islam. Illegal migrations of peoples, religious wars, global pandemics, and the temptations of empire: Rome's end foreshadows our own crises and offers hints how to navigate them—if we will heed this story.