Learn all about four of Istanbul’s most history-filled landmarks; this tour takes you to the beautiful Golden Horn harbour, the great church of St Mary of Blachernae, the church of the Holy Saviour in Chora (also known as the Kariye Museum, in Turkish) and the splendorous Palace of the Porphyrogenitus (Tekfur Palace). Your first stop is one of the most awe-inspiring sights in Istanbul. The Golden Horn is a hornlike branch of the Bosphorus River used as a natural naval harbour in the times of the Byzantine Empire. Its name comes from both its shape and the golden hue it adopts when seen from a hilltop due to the reflection of the sun. Visit the Ecumenical Patriarchate of Constantinople, the seat of Orthodox Christianity in Turkey since the time when Constantine the Great declared Christianity the religion of the Roman Empire. Continue to St Mary of Blachernae, a magnificent church and shrine of the Mother of God famous for its holy water and sacred baths. Then see another breathtaking church, the Holy Saviour in Chora, long ago a Byzantine monastery and nowadays a very interesting museum filled with mosaics and frescoes from ages past. Also delve into the eerie Prison of Anemas, a spooky network of 14 separate dungeons. Finally, visit the imposing 12th-century Palace of the Porphyrogenitus. It is the only surviving pavilion of the Blachernae Palace and it was erected adjacent to the city walls that surround the remains of the Byzantine acropolis; a day full of history.