This work is the result of joint research and field research between the Organization of Cultural Heritage, Tourism and Handicrafts of Iran and the University of Edinburgh, England, in the years 2014 to 2016, that was compiled and published under the joint supervision of Eberhard Sauer, Jebrael Nokandeh and Hamid Omrani Rekavandi. This two-volume book sheds light on Iran's military and defense history during the Sassanid era. Its subject is the archeology of the Great Gorgan Wall, and its purpose is to identify and evaluate one of the large and complex military networks and defense fortifications in northeastern Iran, centered on the Great Gorgan Wall (belonging to the 5th and 6th centuries AD., parallel to the end of the Sassanid era). This book was compiled with a macro interdisciplinary and archeological approach in a historical context. These fortifications and defensive infrastructures have been created to resist the invading tribes that constantly threatened the Sassanid borders from the northeast. The first volume of the book contains the report of archaeological excavations in the studied area as well as a marine archeology program. The second volume includes the results of specialized interdisciplinary researches such as Zooarchaeology, Archaeobotany, palaeography, paleoclimatology, historiography, etc. This book is a turning point in the archeology researches of the Sassanid period in Iran, which, with the cooperation of a large number of researchers and the use of new methods and technologies and a comprehensive view, gave a new spirit to the archeology studies of the Sassanid period. He took it away from the dominant tradition of art history and made it closer to archeology. In addition, against the multitude of studies related to the vigorous rival of the Sassanids, namely the Romans, this work showed that ancient Iran was rightly on par with Rome, as well as one of the two world powers of that time in terms of strategy and defense system.