Hagia Sophia Has Reverted to a Mosque, Erdogan Says

ISTANBUL—President Recep Tayyip Erdogan said Friday that the city’s sixth-century Hagia Sophia, which became a symbol of secularism in modern Turkey when it was converted into a museum in the 1930s, would reopen to Muslim prayer as a full-fledged mosque later this month, a shift opposed by the U.S. and others.

The structure, with its huge dome and towering minarets, has long played a pivotal role in the culture of the city and in Turkey at large. It was built as Christian temple by the Byzantine empire, then became a mosque…