The expansive Imam Mosque courtyard covers 6000sqm with tiled iwans (barrel-vaulted halls) on three sides. But it's the main southwest iwan that's the attraction here, a massive Seljuk structure in mostly uncoloured 10th-century brick. Small remnant sections of original Kufic plasterwork remain. Renovation has added back the missing majority, but in a new style easily differentiated from the original.
Either side of the mihrab are tall ventilation spaces that suggest wind towers might once have topped the iwan.