Used to mark the entry to a reception hall in royal palaces, was adapted by persian architects in the design of mosques.

An Iwan, used to mark the entry to a reception hall in royal palaces, was adapted by Persian architects in the design of mosques. The Iwan is a hall walled on three sides. The fourt side is entirely open. The formal gateway to the Iwan is called Pishtaq. It is a characteristic of the Persian architecture.