structure in Iranian and Islamic architecture

An iwan (Persian: إيوان eyvān) is defined as a vaulted hall or space, walled on three sides, with one end open. Iwans were a trademark of the Sassanid architecture of Persia. They then found their way into Islamic architecture.

Great Mosque of Esfahan, View of the north iwan from the courtyard

Typically, iwans open on to a central courtyard, and have been used in both public and residential architecture.