Originally posted by the Voice of America. Voice of America content is produced by the Voice of America, a United States federal government-sponsored entity, and is in the public domain. Erdogan Faces Backlash Over Plans to Convert Hagia Sophia Into Mosque Dorian Jones ISTANBUL - Turkish President Recep Tayyip Erdogan faces a growing backlash over his plans to turn Istanbul's iconic Hagia Sophia into a mosque. The sixth-century Byzantine cathedral served as a mosque for 400 years before it was turned into a museum. More recently, it was declared a UNESCO World Heritage site in 1985. Throughout the Hagia Sophia's 1,500-year history, its status has reflected the rise and fall of empires. For nearly a millennium, the Hagia Sophia was eastern Christendom's greatest church. But in 1453 when Ottoman forces led by Sultan Fatih Mehmet conquered Constantinople, now Istanbul, his first act on entering the city was to pray in the cathedral and declare it a mosque. .