"The Church of Divine Wisdom". Aya Sofia, Hagia Sophia, however you spell it, it is an amazing building with a long history.
Built in the sixth century as a Christian church, by the time it was conquered by the Turks in 1453 it was the greatest church in the Christian world. After centuries as a Mosque and a centre of learning it became a museum in 1935.
It is simply enormous. I hope the photos give some idea of the scale.
Unfortunately, the signs of age and decay are everywhere, but so are the signs of renovation and preservation. I hope they succeed. Many of the golden mosaics are in very good condition when you look closely, considering their age. It's hard to believe that the gold wasn't all stolen over the millennia.