Sthamer's work is devoted to the description and documentation of the citadels erected by the Hohenstaufen and the rulers of the House of Anjou in Southern Italy and the organization of administrative structures serving the running and upkeep of those fortresses in the 13th century. The present volume is an identical reprint of the original edition published before the First World War in a small number of copies which today are very difficult to obtain. Sthamer's work may legitimately claim exemplary status as a scholarly publication of medieval sources and is of cardinal importance for the political, administrative and regional history of Southern Italy in the 13th century, as well as for the history of art and architecture and medieval construction methods.