Aya Sofya, Istanbul at dusk
Aya Sofya in Turkish (Hagia Sophia in Greek) means "Holy Wisdom" and is a former Orthodox patriarchal basilica, later a mosque, and now a museum in Istanbul, Turkey. From the date of its dedication in 360 until 1453, it served as the Greek Patriarchal cathedral of Constantinople, except between 1204 and 1261, when it was converted to a Roman Catholic cathedral under the Latin Empire. The building was a mosque from 29 May 1453 until 1931, when it was secularized. It was opened as a museum on 1 February 1935.
The Church was dedicated to the Logos, the second person of the Holy Trinity, its dedication feast taking place on 25 December, the anniversary of the Birth of the incarnation of the Logos in Christ. Although it is sometimes referred to as Sancta Sophia (as though it were named after Saint Sophia), sophia is the phonetic spelling in Latin of the Greek word for wisdom – the full name in Greek being Ναός τῆς Ἁγίας τοῦ Θεοῦ Σοφίας, "Church of the Holy Wisdom of God".
Famous in particular for its massive dome, it is considered the epitome of Byzantine architecture and is said to have "changed the history of architecture." It was the largest cathedral in the world for nearly a thousand years, (Wikipedia)