The Imam Reza shrine, located in Mashhad, Iran, is an Islamic shrine containing the remains of Ali al-Rida, the eighth Imam of Shia Islam. It is the largest mosque in the world by area. Also contained within the complex are the Goharshad Mosque, a museum, a library, four seminaries, a cemetery, the Razavi University of Islamic Sciences, and other buildings.

Mashhad is the second-most-populous city in Iran, located in the relatively remote north-east of the country about 900 kilometres from Tehran. In the Central District of Mashhad County, it serves as the capital of Razavi Khorasan Province, the county, and the district. It has a population of about 3,400,000, which includes the areas of Mashhad Taman and Torqabeh.