This book is the first complete description of 13th century architecture in Austria. This period was significant for ist political and historical events and upheavels in the provinces of Austria, but at the same time for the transition from romanic to gothic style. The book is the result of the author's continuous studies in this field of architectural history for more than 35 years. Basing on his doctoral thesis of 1975 the author is outlining a completely new panorama of the development in 13th century architecture by using the results of recent investigations, reconstructions and newly interpreted historical sources. Some important results were achieved on behalf of FWF-projects under the author's direction (reconstruction of the Capella Speciosa at Klosterneuburg, research on the history of the Imperial Palace di Vienna). The results are corresponding in perfect way with the scientifical researches in neighbouring countries as Czech Republic, Hungary, Slovenia and Germany, in regard of the long range cultural communications during the Middle Ages, which in former theories were denied by presupposing a distinct stylistic retard in Austrian architecture.