The Civilization of the Middle Ages: A Completely Revised and Expanded Edition of Medieval History by Norman F. Cantor
This is an insightful and entertaining general treatment of the history of Europe from the fall of Rome to the Reformation. As its name informs, it's less a march through events than a chronologically arranged study of civilizing themes. Cantor's basic thrust is that the West was formed during this period of religious and national development.
