On Saturday, local time, thousands of Muslims turned out to the historic site to protest Turkey's 1934 law that makes it illegal for any religious group to hold services on its grounds. The Hagia Sophia was declared a museum that same year.
"Keeping Hagia Sophia Mosque closed is an insult to our mostly Muslim population of 75 million. It symbolizes our ill-treatment by the West," said Salih Turhan, head of the Anatolian Youth Association.
Turhan said his group staged the protest, in the form of prayers, in light of the upcoming anniversary of the Ottoman Sultan Mehmet's capture of Constantinople, according to Reuters.
"As the grandchildren of Mehmet the Conqueror, seeking the re-opening Hagia Sophia as a mosque is our legitimate right," he told the news agency.
There were also some Greek Orthodox Christians living in Turkey who believe the museum should re-assume its function as a church. However, the Orthodox patriarchate disagrees.
"If it were to become a mosque, Christians wouldn't be able to pray there, and if it became a church it would be chaos," Father Dositheos Anagnostopulos, a spokesman for the patriarchate, told Reuters.
In 2006, Pope Benedict XVI's visit to Hagia Sophia was met by protests from angry Muslims who saw the pontiff's presence as an attempt to make a Catholic claim of the site.
The demonstrators warned that any sign of a prayer there would be considered an offense, BBC News reported, noting that Benedict abstained from making any religious gesture.
According to latest estimates, Turkey's population, numbering around 79.7 million, is 99.8 percent Muslim, while the remaining 0.2 percent are mostly Christians and Jews.
According to Reuters, just a few thousand Greek Orthodox Christians remain in Turkey, although the patriarch's seat is still in Istanbul, as it was before the Ottoman conquest.