Thousands of of devout Muslims from across Turkey gathered and prayed before the historic Hagia Sophia on the 562nd anniversary of the Turkish conquest of Constantinople, demanding that the site be turned back into a mosque.

Men and women from across the country gathered before the Hagia Sophia museum early May 31, as part of an event organized by the Anatolian Youth Association (AGD) with the motto “Break the chains, Open Hagia Sophia,” and prayed the morning prayer with a call for the reconversion of the museum into a mosque.

Designed as an Orthodox Christian basilica in the sixth century by Greek architects Anthemios of Tralles and Isidorus of Miletus, Hagia Sophia was the largest and most significant church in all of Christendom for almost 1,000 years and is now a UNESCO World Heritage site.

Hagia Sophia remained a center of Orthodox Christianity until 1453, when the city was conquered by Ottoman Turks under Sultan Mehmet II. After 916 years of service as a church, he ordered Hagia Sophia to become a “victory mosque,” symbolizing the Muslim conquest. The mosaics of the church were covered with plaster, but they were successfully restored in the 20th century.

After the conquest, Hagia Sophia was used as a mosque for 482 years. Following the Ottoman Empire’s collapse, it was converted into a museum in 1935.