Sultanahmet, İstanbul
The two masterpieces of religion and architecture that Byzantine emperors devoted to the attributes of God, peace and wisdom, are found in İstanbul. Aya Irini (Hagia Eirene) was devoted to Divine Peace and was built before Ayasofya Grand Mosque which was devoted to Divine Wisdom. Both were built by Byzantine Emperor Constantine the Great when the city was founded and were rebuilt several times until the reign of Justinian in the 6th century.
Hagia Eirene, located in the courtyard of Topkapı Palace, was restored and reused during the Ottoman era. The mosaic decoration in the apse is arguably the most noteworthy feature of Hagia Eirene as it is a rare example of Iconoclastic art.
Ayasofya Grand Mosque (Ayasofya Grand Mosque) was first built by Constantine the Great in the 4th century. The final structure was built by Emperor Justinian and used as the main cathedral of the Byzantine Empire for 900 years. In 1453, it was converted into a mosque by Ottoman Sultan Mehmet II following the conquest of Constantinople. Following the restoration work during the Ottoman era and the adding of minarets by architect Mimar Sinan, and architectural features of Islamic tradition, Ayasofya Grand Mosque became one of the most important works of world architecture. After serving as museum for 70 years, Ayasofya Grand Mosque has been reconverted in to a mosque as Ayasofya-i Kebir Cami-i Şerifi (The Grand Mosque) and it is open to visits to all as a timeless monument.
