The Church of Hagia Sophia is located in the center of Nicaea (modern İznik). It served as the venue of the Seventh Ecumenical Council in 787. It originated as an early Byzantine basilica perhaps dating to the second half of the 5th century. It has with a three-sided apse, a narthex, a chapel to the southeast, and probably with galleries. It was severely damaged in the earth of 1065. The lower part of the outer walls consists of regular ashlar masonry (perhaps belonging to a Roman predecessor), while the upper part was built with bricks.