Castles.

Although the design of churches was the primary focus of medieval architectural creativity, structures for the daily living and defense of members of the upper level of society also displayed technical ingenuity and an awareness of the importance of image. Just as the monastery assembled different kinds of buildings—church, hall, infirmary, barn—to accommodate all of the activities—prayer, work, eating, sleeping—of the monk's life, the castle fulfilled an equally varied array of functions in the secular world. With the collapse of the centralized authority and administration of the Carolingian Empire in the later ninth century, power was increasingly concentrated in the hands of local lords. Rather than providing a common defense for the towns under his control, the lord built only for his own security. The great circuits of walls and gateways that had...