Fragment of painted window glass, from the Zeyrek Mosque, 1st half 11th century AD. From the Wikipedia: Zeyrek Mosque (full name in Turkish: Molla Zeyrek Camii) or Pantokrator Monastery (in Turkish: Pantokrator Manastırı), is a significant mosque in Istanbul, made of two former Eastern Orthodox churches and a chapel. It represents the most typical example of architecture of the Byzantine middle period in Constantinople and is, after Hagia Sophia, the second largest religious edifice built by the Byzantines remaining in Istanbul.