This building (Greek: Ἁγία Σοφία; Holy Wisdom) is now known as the Ayasofya Museum, but was an early Christian Church and later an Eastern Orthodox church which was transformed into a mosque in 1453 by the Turks, and converted into a museum in 1935. It is located in Istanbul, Turkey, on the Turkish Thrace. It is regularly considered one of the greatest and most beautiful buildings in history. Its conquest by the Ottomans at the fall of Constantinople is considered one of the great tragedies of Christianity by the Greek Orthodox faithful. The name comes from the Greek name Ἁγία Σοφία, a contraction of Ναός τῆς Ἁγίας τοῦ Θεοῦ Σοφίας, meaning "Church of the Holy Wisdom of God". It is also known as Sancta Sophia in Latin and Ayasofya in Turkish. Although it is sometimes called "Saint Sophia" in English, it is not named after a saint named Sophia — the Greek word sophia means "wisdom."
It was constructed in five years, from 532 to 537, at the orders of Emperor Justinian I and designed by Isidore of Miletus.
I took this photo on a trip to Istanbul in November of 2006.