Constantine XI Palaiologos was the last Christian Emperor of Constantinople and Byzantium. In 1453, when Constantinople fell to the Ottoman Turks, he was last seen fighting at the city walls, but the actual circumstances of his death have remained surrounded in myth. In the years that followed it was said that he was not dead but sleeping - the 'immortal emperor' turned to marble, who would one day be awakened by an angel and drive the Turks out of his city and empire. Donald Nicol's book tells the gripping story of Constantine's life and death, and ends with an intriguing account of claims by reputed descendants of his family - some remarkably recent - to be heirs to the Byzantine throne.