The Zayrek Mosque is the second largest monument of Byzantine architecture that has survived from Constantinople. The church consists of three chapels connected with each other.
The monastery complex in honor of Christ Pantocrator (church, library, hospital) was built by order of the Byzantine king John Komnenos and his wife Irina in the first half of the 12th century. In terms of size, beauty and wealth, the monastery was one of the most famous in Constantinople. The temple was also used as a tomb for the Komnenos and Palaiologos dynasties.
After the Ottoman conquest, the church of Pantokrator became a mosque. It was named after the scientist Moll Zeyrek, who settled nearby and organized a religious school.
For many centuries the building was practically abandoned, but at present the remains of the monastery are being gradually restored.