Hagia Sophia Museum/Church Introduction: Hagia Sophia Cathedral is one of the top ten most coveted churches in the world, across the street from the Blue Mosque. It was built during the reign of the Eastern Roman Emperor Justinian (532 AD - 537 AD). It is an imposing rectangular stone building with a huge dome, 31 meters in diameter and 55 meters above the ground. There are 40 large glass windows and 4 majestic arches around the bottom, which is a typical Byzantine architecture. After the fall of the Byzantine Empire in 1453, the Turks who believed in Islam built four minarets outside the church and converted this thousand-year-old cathedral into a mosque. In 1935, after the establishment of the Turkish Republic, it was converted into a museum.