Mashhad is the second most populous city in Iran and is the capital of Razavi Khorasan Providence which located in north east of Iran, close to the borders of Afghanistan and Turkmenistan. The population of Mashhad was recently about two and a half millions. The name Mashhad comes from Arabic meaning the place of martyrdom the place where Imam Reza, the eight Imam of Shia Muslims, was martyred. Imam Reza Shrine is the largest mosque in the world by dimension and second largest in capacity with other buildings inside the complex including the old Goharshad Mosque. The Imam Reza Shrine complex is the center of tourism in Iran in which every year ceremony of Dust Cleaning is celebrated in the Imam Reza Shrine.