The site - built as a Christian cathedral, has been a museum and mosque over the years

Friday prayers are being held in the historic Hagia Sophia in Istambul for the first time since the iconic building was officially re-purposed as a mosque by President Recep Tayyip Erdogan's government. Built in the sixth century as the premier cathedral of the Roman Empire, it was the largest church in the world for almost 1,000 years. Throughout it's history, it has been used as a mosque and most recently as a museum. Neighbouring Greece has said that the re-designation as a mosque "deeply hurts those who consider this top symbol of Christianity to belong to humanity and the world’s cultural heritage". Tulin Daloglu, chief editor of halimiz.com, explains why this is such an important day for Turkey's President Erdogan. (Photo: The Hagia Sophia in Istanbul. Credit: Getty Images)