Defensive fortifications in different regions of Iran have been an effective factor in the survival of residential centers and commercial routes. An investigation on defensive structures will provide useful information on this kind of architecture. The study of remains of castles in the Rey region has provided an important context for archaeological research. In the present study, the Seljuk fortifications (Rashkān fortress, Gabri and Kāsni Castles) are introduced and recognized as inner city castles. It aims at identifying and studying the Seljuk fortifications of Rey, identifying the function of inner city fortifications, and comparing them with other samples in neighboring regions in terms of characteristics. The data were gathered through field and documentary studies while an analytical-historical method was applied in the course of the research. Important questions intended to be addressed were: 1. what has been the role of Seljuk fortifications of Rey in security provision of the region? 2. In which categories can the Seljuk fortifications of Rey be classified in terms of structural characteristics and architectural classification? Among the Seljuk fortifications of Rey, Kohandez (e.g. Rashkān Fortress) had functioned as the political headquarters, and in other inner city castles, larger circular towers have been usually located in four angles and interspersed with subsidiary towers. These types of defensive architecture indicate the progress in the urban construction and security provision.
