Hagia Sophia is one of the most fascinating religious buildings in history. Located in Istanbul, Turkey, it has served as a great Christian basilica, a mosque, and a museum with each chapter of its story leaving behind a unique mark on its impressive architecture and iconic aesthetic. Originally built by Byzantine Emperor Justinian I in 537, Hagia Sophia was the largest church in Christendom for almost a millennium. In 1453, the Ottoman Sultan Mehmed II transformed it into a mosque, constructing minarets, mihrab, a minbar, and a grand chandelier. Today, Hagia Sophia serves as a museum, preserving both the Islamic features and the Christian mosaic and frescoes which adorn the walls. It is considered to be one of the world’s greatest monuments and it continues to awe visitors from all over the globe each year.