Hagia Sophia

Meaning "Church of Wisdom", this church was built by Emperor Justinian of the Byzantine Empire. For one thousand years this giant Orthodox basilica reigned supreme as the worlds largest Cathedral in the world, until the Seville Cathedral was built in 1520. The church contained Holy Relics such as a 49 foot silver iconostasis. It was also the seat of the Eastern Patriarch and was the religious focal point for the Eastern Orthodox Religion. It was also the site of the place where the start of the Great Schism took place with the excommunication of Cerularius by Cardinal Humbert. In 1453 Constantinople was conquered by the Ottoman Turks and the basilica was converted into a mosque where the bells, whistles, iconostasis, and sacrificial vessels were removed along with the mosaics being plastered over. Finally in 1935 the mosque was converted into a museum where the relics and building itself can be viewed by everyone.

http://en.wikipedia.org/wiki/Hagia_Sophia