The magnificent Hagia Sophia was built at the behest of the Byzantine Emperor Justinian in 537 BCE, then known as the Church of the Holy Wisdom. A remarkable testament to the ingenuity of the Byzantine architects, the Hagia Sophia was built upon a design that was rather unique for its time. The Turkish conquest of Constantinople marked the beginning of a new chapter in the history of the Hagia Sophia. Re-purposed by Mehmed II to be used as a mosque, its gold mosaics and frescoes were painted over with Islamic motifs and patterns. A few of these have since been uncovered, preserved for centuries beneath layers of plaster. The emperor also added minarets and added massive discs bearing Arabic calligraphy to the grand scheme. One of Istanbul's most recognizable and iconic landmarks, the Hagia Sophia is an ode to both the Byzantine and Ottoman penchant for art and architecture.