We start in Istanbul about the time we left off at the Greek/Roman era sites -- ca. 300-400 a.d., when the city was coming into power as the new capital of the Roman empire.  To the right is Bimbirdirek Cistern, the oldest in Istanbul, dating to 300 CE - the year that Constantinople was dedicated as "New Rome" (a previous settlement known as Byzantion dates to 660 BCE).

Above: The Church of Hagia Sophia (Holy Wisdom) - built by the Emperor Justinian in 523 CE - unlike any previous church and standing as the greatest sacred building of Christendom for a millenium.  It was looted during the crusades and converted into a mosque when Istanbul was conquered by the Turks, at which point the four minarets were added.  The architecture, especially the dome, served as a model for other mosques. 

Below & Right: the Kariye Museum - previously the Church of St. Savior in Chora (ca; 500 CE) - containing numerous frescoes telling biblical stories from the Eastern Orthodox tradition.

Now we move on to the conquest of Constantinople in 1453 by Mehmet II the Conqueror.  At right, Mehmet's castle and fortifications.  Below, Fatih ("Conqueror") Mosque - built 1463-1470.

Right: Rustem Pasha Mosque (1561) - beautiful ceramic tiles.

Below: Sulimanye Mosque (1557) - Supposed to be the most architecturally perfect mosque.

The Blue Mosque (1609-1616) - the grandaddy of them all - six (!) minarets.  A symbol of Ottoman power.