This horn-shaped estuary divides European Istanbul. One of the best natural harbours in the world, the Byzantine and Ottoman navies and commercial shipping interests were centered here. Today, lovely parks and promenades line the shores where the setting sun dyes the water a golden colour. At Fener and Balat, neighbourhoods midway up the Golden Horn, whole streets of old wooden houses, churches, and synagogues date from Byzantine and Ottoman times. The Orthodox Patriarchy besides here at Fener. Eyup, a little further up, reflects the Ottoman style of architecture. Cemeteries sprinkled with dark cypress trees cover the hillsides. Many pilgrims come to the tomb of Eyup in the hope that their prayers will be granted. The Pierre Loti Cafe, atop the hill overlooking the shrine is a wonderful place to enjoy the tranquillity of the view. Istanbul is an international art and cultural centre.

The seat of world Orthodoxy and home to the 270th successor of the Apostle Andrew is a surprisingly humble complex of buildings in the Golden Horn neighborhood of Fener. The 17th-century Church of St. George's magnificent gold-leaf altar bears important icons, and relics of major saints rest in the cathedral's narthex. Since the fall of the Ottomans, the Greek population of Istanbul has largely emigrated, so today the church is more of a symbolic center for the Ecumenical Patriarchate than anything else. But the spiritual leader of the world's 300 million Orthodox, Bartholomew I, continues to hold services here, and Orthodox Christians from Greece and across Eastern Europe stream through the church as pilgrims. Stop for a rest in the pleasant garden full of friendly cats.

In 450, Empress Aelia Pulcheria started to build a church near a fountain of holy water situated outside the walls of Theodosius II at the foot of the sixth hill of Constantinople. After her death, in 453, the shrine was completed by her husband, Emperor Marcian. Emperor Leo I erected near the church two other buildings: a parekklesion, named Ayía Sorós, since it hosted the holy mantle and robe of the Virgin brought from Palestine in 473, and the ´Ayion Loúsma ("sacred bath") edifice, which enclosed the fountain. The importance assumed by the whole complex encouraged the Emperors to lodge in the surroundings and to build there the nucleus of what would in later centuries become the imperial palace of Blachernae. During the first quarter of the 6th century, Emperors Justin I and Justinian I restored and enlarged the church. The name of Blachernae may come from the old name of Romanians (Vlach, Blac, etc.) and from a small colony of Vlachs.

The Palace of the Porphyrogenitus, known in Turkish as the Tekfur Sarayı ("Palace of the Sovereign"), is a late 13th-century Byzantine palace in the north-western part of the old city of Constantinople (Istanbul). An annex of the greater palace complex of Blachernae, it is the best-preserved of the three Byzantine palaces to survive in the city (together with the ruins of the Boukoleon Palace; and the ruins of the Great Palace of Constantinople with its surviving substructures, retrieved mosaics and standing Magnaura section), and one of the few relatively intact examples of late Byzantine secular architecture in the world. The Palace was constructed during the late 13th or early 14th centuries as part of the Blachernae palace complex, where the Theodosian Walls join with the later walls of the suburb of Blachernae. The palace appears at first glance to be named after the 10th-century emperor Constantine VII Porphyrogenitus.

(Good news! After many years of restoration Chora is back!) After the Istanbul conquest, the church became a mosque in the 16th century, and after a series of restorations, it became a museum in 1958. The Chora Museum, a former orthodox church, has one of Istanbul's most beautiful interiors. The Chora Church is considered one of the finest remaining examples of Byzantine Architecture and serves as a museum on the European side of Istanbul in Edirnekapi district of Fatih. Today, in the beautiful neighbourhood of Wood Hotels and cafes, this wonderful museum attracts thousands of believers..

The Basilica of St. Sophia, now called the Ayasofya Museum, is unquestionably one of the finest buildings of all time. Built by Constantine the Great and reconstructed by Justinian in the 6th century, its immense dome rises 55 meters above the ground and its diameter spans 31 meters. You should linger here to absorb the building's majestic serenity and to admire the fine Byzantine mosaics. (Open every day except Monday).

One of the main examples in military architecture is the 6,650 metres in city walls of Theodosius II, with its second line of defences in 447. City Walls are one of the largest projects of the Ancient Period and are situated on the western frontier of the Historic Peninsula, from Golden Horn to the Marmara Sea in the north-south direction. The walls are of high quality with their scale, nature, construction techniques and materials. Their construction was launched at the beginning of the 5th century under the reigns of Emperor Theodosius II. The Byzantine city walls surrounded the acropolis of Byzantium with 22 kilometres of fortification including 96 towers and 9 main gates.