The eastern fortification complex of Eski-Kermen consists of a defensive wall between towers IV and VI, towers V and VI, the eastern entrance to the city, a fortress granary, and a siege well. The cave rooms of the towers are cut into 30–44-meter-high rocky promontories protruding from the eastern façade of the plateau. According to N. I. Repnikov, the Goths built the castle atop the plateau of Eski-Kermen in the late fifth century. A. A. Vasiliev, A. L. Yakobson, and M. A. Tikhanova considered that the Eski-Kermen defensive complex, along with other the fortifications of the limes Tauricus, was created in the sixth century to protect the land of Dory from nomads, according to the order of Justinian I. In E. V. Veimarn’s view, the castle appeared in the late fifth century in the course of development of feudal relations among the local Scythian and Sarmatian populations. In contrast to N. I. Repnikov’s and E. V. Veimarn’s interpretations, the fortifications considered in this article show nothing comparable to the Gothic or Taurian techniques of building. It is quite obvious that the castle on the plateau was designed and erected according to a project of an experienced Byzantine military engineer. The date of the construction of the castle is determined by a complex of ceramic ware uncovered in 2006–2007 by the excavations of the layer which developed when the eastern defensive wall had been erected. The construction of the wall and, therefore, the creation of the castle was simultaneous with the age of Emperor Maurice (582–602).