Architectural products and related elements and components are produced under the influence of cultural conditions, needs, technical experiences of the society, creativity and many other factors and evolve over time. Moreover, in different historical periods, the entrance and its components have also changed. Since the entrances due to their functional role and importance as well as their location in the architectural spaces and urban fortifications were the first elements that were damaged and destroyed in times of crisis, for a systematic review of the evolution of the entrances, there are no appreciable items from the oldest examples. On the other hand, in recent decades, the changes caused by development and destruction have also destroyed or transformed many of the remains of cities and architectural complexes. Since then, the registration, recording and protection of the rest entrances has attracted the attention of those interested. Therefore, the issue of entrance in Iranian architecture is still a less well-known issue and it seems that the evolution of access from simple pre-historic entrances to complicated entrance devices of historical periods is a subject worthy of contemplation and to achieve Such a purpose, especially in the case of the prototypes, the use of archeological findings is considered the only possibility of examining the entrances. Based on these findings, the present article investigates the changes and transformations of the entrances from the first obtained samples until the Sassanid period. The effort has been to track and highlight the changes and transformations of the entrances in the mentioned time frame by using the archaeological reports, documents and the existing samples.