The Imam Reza Shrine (Persian: حرم امام رضا‎‎) in Mashhad, Iran is a complex which contains the mausoleum of Imam Reza, the eighth Imam of Twelver Shiites. It is the largest mosque in the world by dimension and the second largest by capacity. Also contained within the complex are the Goharshad Mosque, a museum, a library, four seminaries, a cemetery, the Razavi University of Islamic Sciences, a dining hall for pilgrims, vast prayer halls, and other buildings.

The complex is one of the tourism centers in Iran. The shrine itself covers an area of 267,079m2 while the seven courtyards which surround it cover an area of 331,578m2 – totaling 598,657 m2 (6,443,890 sq ft).

Every year the ceremony of Dust Clearing is celebrated in the Imam Reza shrine.