The Hagia Sophia in Istanbul, Turkey, was completed in 537 as a Greek Orthodox church, serving in this capacity until 1204, when it became the main Roman Catholic cathedral of the Latin Empire. Consecrated again to the Orthodox faith in 1261, it became a mosque in 1453, following the fall of Constantinople. The architectural style of this former basilica, including its large dome, influenced the architecture of Ottoman mosques, including that of the Blue Mosque, which replaced the Hagia Sophia as the principal mosque of Istanbul in the early 1600s. In 1931 the mosque was closed to the public, secularized, and then reopened as a museum; it is now a common tourist destination.Photograph: Arild Vågen