Hagia Sophia Museum
The Hagia Sophia, the biggest church constructed by the East Roman Empire in Istanbul, has been constructed three times in the same location. Constructed by Emperor Konstantios (337-361) in 360, the first church was named Megale Ekklesia (Big Church); however, after the fifth century, it was referred to as the Hagia Sophia (Holy Wisdom). As it burned down after the public riot that took place in 404, a second church was reconstructed by Emperor Theodosios II in 415. It was again demolished in 532, after another the public riot that took place during the fifth year of Emperor Justinian’ reign.
The current church was constructed by Emperor Justinian’s orders. All the walls of the Hagia Sophia except the ones covered by marble have been decorated with exceptionally beautiful mosaics. Gold, silver, glass, terra cotta and colorful stones have been used to make the mosaics. It remained the world's largest cathedral for nearly a thousand years thereafter, until Seville Cathedral was completed in 1520.
After the conquest of Istanbul by the Ottoman Empire, it was converted into a mosque. The 7.5-8 m diameter calligraphy panels were placed in the main walls of the structure. The panels that read “Allah, Hz. Muhammed, Hz. Ebubekir, Hz. Ömer, Hz. Osman, Hz. Ali, Hz. Hasan and Hz. Hüseyin” are known to be the biggest calligraphy panels in the Islamic world. Since 1935, Hagia Sophia as been used exclusively as a museum.