Hagia Sophia

Hagia Sophia, originally uploaded by petrosg.

Hagia Sophia 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 cathedral of Constantinople. 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.

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, until Seville Cathedral was completed in 1520. The current building was originally constructed as a church between 532 and 537 on the orders of the Byzantine Emperor Justinian and was the third Church of the Holy Wisdom to occupy the site, the previous two having both been destroyed by rioters. It was designed by the Greek scientists Isidore of Miletus, a physicist, and Anthemius of Tralles, a mathematician.

In 1453, Constantinople was conquered by the Ottoman Turks under Sultan Mehmed II, who subsequently ordered the building converted into a mosque. The bells, altar, iconostasis, and sacrificial vessels were removed and many of the mosaics were plastered over. Islamic features — such as the mihrab, minbar, and four minarets — were added while in the possession of the Ottomans. It remained a mosque until 1931 when it was closed to the public for four years. It was re-opened in 1935 as a museum by the Republic of Turkey.

Source: Wikipedia