Gohar Shad Masque in Mashhad
Built 1405 - 1418
Gohar Shad was the wife of  Mongol ruler, Shahrokh.  She ordered construction of this mosque.
This mosque is located in the south side of Imam Reza Shrine.
It has a four ivan court (317 by 277 ft)  which is surrounded by a two story arcade, used for religious teaching and gatherings

The IranOnline.com