When the Ottoman Empire collapsed, Turkey became a secular republic. Its first president Mustafa Kemal Atatürk ordered in 1934 that the temple serving more than 916 years to Christians and 481 years to Muslims, be turned into a museum.

In 2020, an administrative court in Turkey annulled the 1934 decree converting Hagia Sophia into a museum. Hagia Sophia once again became a mosque. The site remains open to visitors outside of prayer times. Entrance is free of charge.