Each year, hundreds of thousands of pilgrims make their way to the city of Mashhad in north-eastern Iran. Mashhad is the nation’s holiest city. It houses the tomb of Imam Reza, the only imam, or spiritual leader, who is buried in Iran.

After invaders destroyed the original tomb, Shah Abbas the Great ordered construction of the present tomb. It is covered with a gold dome. Blue tiles decorate the walls and fountains bubble in the courtyard. Inside, Imam Reza’s body rests behind a golden gate. Non-Muslims may walk quickly across the courtyard, but they are forbidden to enter the holy shrine itself.