Chora Museum ( Kariye Müzesi)

The Chora Church (Turkish Kariye Müzesi, Kariye Camii, or Kariye Kilisesi ) is the most important Byzantine monument in Istanbul after Haghia Sophia. It is situated in the western, Edirnekapı district of Istanbul. The dictionary meaning of Kariye (Chora) is "outside of the city", or "rural" in old Greek. The existence of a chapel outside the city walls in ancient times is mentioned in some sources. The first Chora Church was built on the site of this chapel by Justinianus. The building that managed to survive until the Commenos with several additions and repairs, gained importance when the Imperial Palace Blakhernia near the city walls was expanded. At the end of 11th century Maria Dukaina, the mother-in-law of Emperor Alexi I had it rebuilt. The building was used as a church after the conquest of Istanbul in 1453, then converted into a mosque in 1511 by the Vezir Hadım Ali Pasha, who later added a school and a kitchen next to it. After the conversion, the mosaics and frescoes were covered either by wooden works or by whitewashing. All the mosaics and frescoes were again uncovered between 1948 and 1958 by the American Institute of Byzantine Research. Chora mosaics and frescoes are the most stunning examples of the last period of Byzantine art (14th century).

http://www.learn.columbia.edu/byzantium/html/building_history.html