City in Turkey, now called Iznik. Location of the Council of Nicaea, the first in 325 A.D., when Emperor Constantine of Byzantium called all the bishops of the Catholic Church together, of which 318 appeared. This was the first Ecumenical Council of the Catholic Church. The Second Council of Nicaea was in 787.
Nicaea was taken in 1327 by the Ottoman Empire, another stepping-stone on their way to Ottoman control of all Turkey.