THE GREAT AGES OF WORLD ARCHITECTURE OVER 100 ILLUSTRATIONS INCLUDING PHOTOGRAPHS, PLANS AND DRAWINGS Until the eleventh century two distinct architectural styles, nourished by different roots, flourished in the medieval world. The Carolingian-Ottonian tradition developed multiple levels of form and meaning. Beginning with the rather simple architectural treatment needed for a single martyrium, Carolingian art finally produced Charlemagne’s Palace-Chapel at Aix-la-Chapelle, the major monument of that age. The compound forms exemplified by double apses and multiple crypts led toward a complex treatment of inter-penetrating forms and spaces, culminating in the sophisticated great cathedral at Speyer.