Dominating the old city, this magnificent building has a tiled entrance portal that is one of the tallest in Iran, flanked by two magnificent 48m-high minarets and adorned with an inscription from the 15th century. The exquisite mosaics on the dome and mihrab, and the tiles above the main western entrance to the courtyard are particularly stunning. The gardoneh mehr (swastika symbol) used on the tiles symbolises infinity, timelessness, birth and death and can be found on Iranian buildings dating back as early as 5000 BC.
Built for Sayyed Roknaddin in the 15th century, the mosque is on the site of a 12th-century building believed to have itself replaced an earlier fire temple. In the courtyard there is a stairwell leading down to part of the Zarch Qanat (closed to the public). Roof access is barred to everyone except Muslim women, who are allowed up on Fridays only.
Source: Lonely Planet