Security and safety have always been fundamental concerns for human beings. Therefore the They have always been in search of ways to mitigate risks which leaves them vulnerable to threats .Vulnerability in principal is the damages caused by actual and potential destructive factors and phenomena. For this reason, humankind has always searched ways for putting up defense against these damaging circumstances. Since Iran has always been historically the subject to military attack either as the target or on the way of invasion of neighboring nations and tribes, one of the innovative ways to sustain settlements was using passive defense methods and strategies to reduce vulnerability of communities. Security and defense strategy and corresponding measures have had deep influences on shaping the settlements and transformation of their fabrics. A defensive consideration in architecture was an indispensable aspect of historical urban and rural fabrics. The risks of enemy attack as well as natural hazards (such as strong desert winds) have greatly affected the form and function of traditional settlements. Designing fortifications and citadels in high places to scout, building towers, ditches, moats, fences and gates on roads and tracks for traffic control etc. are among architectural elements of such passive defense. Some of these elements can be found in Mohammadieh, which is located in the center of Iran next to the ancient path of Isfahan to Khorasan provinces.
There are two kinds of citadels in Mohammadieh. The first one is mountain citadel, which is located in the highest place for temporary settlement of the villagers at the time of adversary attacks and invasions. The second one is castle called “Rig Castle” in Sheikh Zeinodin district, which has been for living of laborers and livestock of the local property owner. “Hakim Dolat” gate in Pa-Derakht district and “Meidan Bala” gate are the other defense elements of Mohammadieh village. Mohammadieh village is part of Isfahan province and the Nain County and has valuable historic rural fabrics. Like many in the hot and dry areas, influenced by the regional hot arid climatic conditions, this village possesses a compact fabric. This compact form is closely surrounded by gardens and farms. In addition to its livelihood role of providing agricultural production supplies, this green belt has a fundamental role as a protection layer for the central fabric of the village in against adverse environmental circumstances such as desert winds, dust storms and dry airflows. Together with the compact residential fabric and their narrow and winding alleys, they helped to strengthen the defense system of the city and slowing down the assailants. This study focuses on variety of passive defense tactics in Mohammadieh village and understanding how defense strategy affected architecture and its physical settings. In doing so analytical and descriptive methods based on field studies and visual evidences, using library resources as well as interviews with local residents. The results showed that in Mohammadieh village, apart from the citadel fortifications and gates that are explicit elements of the defense system, compact and complex rural fabric with organic indirect network of alleys are implicit elements of passive defense.