The Patriarchate at Fener, by the Golden Horn, is the heart of Orthodox Christianity. After Constantine the Great' s declaration of Christianity as the religion of Roman Empire, the capital was moved from Rome to Byzantium. With the conquest (1453) of Ottoman Empire, the seat of Patriarchate remained in Istanbul.
Church of Panagia of Blachernae, the best known and most celebrated shrine of the Holy Virgin located near Golden Horn, famed with the hagiasma (fountain of holy water), good to cure health problems, and the Hagion Lousma (sacred bath) good to clean the soul where the emperor also came to purify himself.
St. Savior in Chora (Kariye Museum), originally a Byzantine monastery, dedicated to Jesus Christ the Savior, survived with fantastic mosaics and frescoes, portraying scenes from the Bible, the life and miracles of Jesus.
Pantocrator (Zeyrek Mosque), the monastic complex was one of the largest and best organized of the Byzantine period, comprising two churches and a funerary chapel, baths, a hospice for the aged, a hospital and a medical school, a hostel for travellers and a library.
Church of St. Mary Pammacaristos (Fethiye Mosque), built in the 11th century by John Comnenus, displaying the aesthetic refinement attained to Paleologan Age, originally belonged to a convent of nuns. Housed the Patriarchate for a while after the conquest.
Zoodochos Pege at Balikli, dedicated to the Mother of God at Pege, with an underground cistern, full of gold fishes related to a well-known miracle, and the fountain of holy water.
St. Sergius & Bacchus, a landmark in Byzantine ecclesiastical architecture. Today it is known as the "Little Hagia Sophia” because its general plan is a precursor of the Hagia Sophia.
Hagia Eirene, the old patriarchal church with its impressive size stands next to Hagia Sophia.
Hagia Sophia, for many centuries was the largest church of Christendom, dedicated to Divine Wisdom, an attribute of Christ. Hagia Sophia played an important role as emperors were crowned and many victories were celebrated in this remarkable building.