The Imam Reza Shrine 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 .