Hagia Sophia, officially known as the Great Blessed Mosque of the Great Hagia Sophia, and also known as the Hagia Sophia, is one of the main places of worship in Istanbul.
Dedicated to Sophia (the wisdom of God), from 537 to 1453 the building was a Christian cathedral (seat of the Patriarchate of Constantinople, except for a short period between 1204 and 1261 when it was converted by the Crusaders under the Latin Empire of Constantinople to Roman rite catholic cathedral).
It became an Ottoman mosque on May 29, 1453 and remained so until 1931, when it was deconsecrated. On 1 February 1935 it became a museum. On 10 July 2020, with a presidential decree, it was again opened to Islamic worship. On the following 24 July, the first Islamic public prayer took place in the presence of the Turkish president Erdoğan.