Turkish President Recep Tayyip Erdogan arrived at the Cathedral of Hagia Sophia an hour earlier to attend the first Friday prayer after re-converting the cathedral into a mosque, Sabah reported.
Mosaics depicting Christian figures in Istanbul's ancient Hagia Sophia were covered with curtains during Muslim prayers.
Turkish President Recep Tayyip Erdogan has earlier signed a decree on converting Hagia Sophia into a mosque.
Erdogan shared on Twitter a copy of the decree he had signed according to which the decision had been taken to hand control of 'the Ayasofya Mosque, as it is known in Turkish, to the country’s religious directorate and reopen it for worship.'
A Turkish top administrative court ruled Friday in favor of a proposal to turn the Hagia Sophia museum back into a mosque.
According to Anadolu Agency, thus, the court annulled a 1934 presidential decree converting Hagia Sophia into a museum.
The Hagia Sophia was the Roman Empire's first Christian cathedral: it was converted from a Greek Orthodox cathedral to a mosque in 1453 and then became a museum in 1935.
UNESCO has earlier warned Turkey against turning Hagia Sophia into a mosque, calling for dialogue.
The Hagia Sophia is inscribed as a UNESCO World Heritage site.