As elite communities in medieval societies the Military Orders were driven by the ambition to develop built environments that fulfilled monastic needs as well as military requirements and, in addition, residential and representational purposes. Growing affluence and an international orientation provided a wide range of development potential. That this potential was in fact exploited may be exemplified by the advanced fortifications erected by Templars and Hospitallers in the Levant. Although the history of the Military Orders has been subject of research for a long time, their material legacy has attracted less attention. In recent years, however, a vast range of topics concerning the Orders' building activities has become the object of investigation, primarily with the help of archaeology. They comprise the choice of sites and building materials, provision and storage of food and water, aspects of the daily life, the design and layout of commanderies, churches and fortifications, their spatial arrangement, and the role these buildings played in their environmental context. This volume contains ten articles discussing the archaeology and architecture of buildings erected by the three major Military Orders in different geographical regions. They cover most countries of Western Europe and include a number of important fortifications in the Levant. These studies break new ground in the investigation of the built fabric of the Military Orders. Written by noted international scholars this publication is an important contribution to modern research on these institutions, which, in their association of monasticism and knighthood, were so typical for the Middle Ages.