Aachen Palace Complex (c. 784–796)—Located in Aix-la-Chapelle in what is now Germany, the Aachen complex was one of fourteen residences of the emperor Charlemagne. Based on specific Roman prototypes, the buildings were intended to convey and legitimize the idea that Charlemagne was the successor to western Christian Roman rule.

Avignon Palace Complex (c. 1335–1345)—While Avignon served as the seat of the papacy during the early fourteenth century, this complex was constructed as a grand papal residence with two huge palaces around a large walled courtyard, with defensive towers at either end. From the outside, it remains today a fine specimen of military architecture, while on the inside it is a repository for grand wall paintings.

Canterbury Cathedral (1100–1175)—This site was both the seat of the diocese's archbishop—the spiritual center of the English church—and also, after 1170, an...