The president of Turkey on Friday formally converted Istanbul's sixth-century Hagia Sophia back into a mosque and declared it open for Muslim worship, hours after a high court annulled a 1934 decision that had made the religious landmark a museum.

The decision sparked deep dismay among Orthodox Christians. Originally a cathedral, Hagia Sophia was turned into a mosque after Istanbul's conquest by the Ottoman Empire, but had been a museum for the last 86 years, drawing millions of tourists annually.There was jubilation outside the terracotta-hued structure with its cascading domes and four minarets. Dozens of people awaiting the court's ruling chanted "Allah is great!" when the news broke. A large crowd later prayed outside it.