The external shell and the physical characteristics of the building have always played an essential role in Iranian architecture and its function has been various in different periods and has always been influenced by cultural and social conditions throughout history. The diversity of this layer of architecture in the first Pahlavi period is more visible than other periods. Because by employing foreign architects, especially German, the Iranian government provided the basis for the emergence of different architectural styles with different physical characteristics. The main question of the research is that what are the components and features of the physical structure and the external layer of architecture in this period which is influenced by the presence of the Germans in Iran? The present research is of qualitative type and based on historical documents and field perceptions, based on descriptive-analytical method, will deal with the role of German architects in the emergence and appearance of physical features in the architecture of Pahlavi the first period. The results show that German architects have influenced the physical aspects and the external shell of architecture in the aforementioned period in two ways; First, the use of German architectural capabilities through lived experience and its transfer to Iran, and second, the use of pre-Islamic and post-Islamic architectural features.