The Masjed-e Jameh's four lofty iwans originally date from 1349, though there was extensive modernisation during the Safavid and later periods. Instead of a minaret there's a squat clock tower atop the main (eastern) entrance portal, where beautifully detailed tiling includes Allah/Ali cryptograms raised above the surrounding surface.
There are entrances from Qadamgah Bazaar, Dr Shari'ati St and from Shohada Sq (main).