A "parekklesion" is the Greek word for a chapel. The Church in the Chora Monastery in Istanbul (Turkey) had a chapel, or burial chapel, where members of the Imperial Family were buried. The church itself contains some of the best preserved mosaics of that period. The Parekklesion however contains frescoes of scenes of the Old Testament.
The Chora Church is one of the most beautiful examples in existence of the Middle Byzantine Period (843-1204).