It is known that works concerning Istanbul and Hagia Sophia began to be written, either through translation or original composition, shortly after the conquest of Istanbul by the order of Fatih Sultan Mehmed Han (d. 886/1481), and this tradition continued in subsequent periods. This work brings together three treatises on the history of Hagia Sophia. The first was translated from Greek into Persian in 885 (1480) by Derviş Şems, known as Şems-i Harâbâtî, by the order of Fatih Sultan Mehmed. The second treatise, also dating back to the Fatih period, was written by an anonymous author in the same year, 885 (1480). The third treatise was authored by Ahmed b. Ahmed el-Münşî el-Cilânî in 905 (1499) in the name of Sultan Bayezid II. These treatises are among the oldest sources written in the Islamic world regarding Hagia Sophia and Istanbul. In the analysis section of the work, based on the contents of the three treatises that form the foundation of this study, topics such as the history of Istanbul and the idea of constructing Hagia Sophia, the determination of the site for the Hagia Sophia building, the gathering of materials, design and construction of the building, the name and meaning of Hagia Sophia, the financial source for its great dome, the construction of this great dome, the decorations of Hagia Sophia, the completion of the Hagia Sophia building, the death of Justinian and the reign of Justin II who succeeded him, the collapse of the great dome of Hagia Sophia, and finally, the conquest of Istanbul are explained.