Located on a hillside overlooking the Golden Horn (“Haliç”) in the Fatih district, Zeyrek Mosque is the second largest religious structure built by the Byzantines still standing in Istanbul, the biggest being Hagia Sophia.
It comprises three buildings: two former Eastern Orthodox churches and a chapel. There’s a very nice restaurant nearby called Zeyrekhane where you can have something to eat or drink after your visit.
Note that the opening hours change daily depending on prayer times.
Mon-Su: 09:00-21:30