The first Muslim prayers in Istanbul's Hagia Sophia are expected to be performed on July 24, and admission to the mosque will be free for everyone, Turkish President Recep Tayyip Erdogan said on Friday, soon after signing a decree to reconvert Hagia Sophia into a mosque.

"Upon the completion of preparatory works, which are now being conducted quite quickly, we plan to open Hagia Sophia for prayers on July 24, the same day when the Friday prayer will be performed," Erdogan said in his address to the nation.

Entrance to the mosque will be free, the Turkish leader assured.

"As Hagia Sophia has lost its status of a museum, paid admission is cancelled. Just like all the other mosques, Hagia Sophia will be open for everyone: locals, foreigners, Muslims and representatives of other faiths," Erdogan added.

Shortly after his announcement, the first call to prayer since the Turkish government converted the mosque into a museum in 1934 came from Hagia Sophia.

The Church of the Holy Wisdom was completed in 537 AD during the reign of Byzantine Emperor Justinian the Great, and remained the main cathedral of the Orthodox Church until the conquest of Constantinople by the crusaders in 1204, after which the building was briefly turned into a Catholic cathedral. 

In 1261, the Byzantines recaptured the city and the Church of the Holy Wisdom once again became the main Orthodox cathedral.

Nearly two centuries later, in 1453, the city was conquered by the Ottoman Empire and turned into a mosque. It remained a mosque until 1931 when it was closed to the public for four years. It was re-opened in 1935 as a museum by the Republic of Turkey.