Pope Francis on Sunday said that he was “very pained” by Turkey’s decision to convert Istanbul’s Hagia Sophia museum into a mosque.

“My thoughts go to Istanbul. I think of Santa Sophia and I am very pained,” he said during his weekly blessing.

Turkish President Tayyip Erdogan has said that the first prayers would be held in Hagia Sophia on July 24. He said the nearly 1,500-year-old Hagia Sophia, which was once a Christian cathedral, would remain open to Muslims, Christians and foreigners.