Entering the ancient doorway you step into a small enclosed Hashti, or hallway. Here you are forced to redirect your steps away from the street and the opportunity is given to purify yourself before entering the mosque, using water from the large font seen in this illustration.
The Hashti, a concept borrowed from domestic architecture, enables the architect to turn the steps of the believer into the correct orientation for prayer, as well as marking a transitional space between the eivan which leads into it and the courtyard which becomes its culmination. By later Safavid times this design was well established and this is an excellent example of its use.