The Byzantines gave special importance to Trabzon from the military point of view. During the reign of Emperor Justinian in the 6th century the city walls were thoroughly repaired and enlarged. A road from Trabzon to Persia was opened. Huts for defense were built at bends and effort was given to establish Christianity so that the tribe Can, the dwellers along the road would be obedient. Aqueducts of Saint Eugenius were built.
In the 8th century the Moslem Arab armies entered Anatolia and came down to Trabzon, invading the area around the citadel. They saw hazel nuts for the first time.
In the 9th century the Moslem Turkish armies started coming to the Trabzon area and outer part of the citadel went under the sovereignty of the Moslem Turks. Inside the citadel there were still the Greek colonists. It is in this period that construction of the Saint Ann Church in the Ayvasil district completed. As a matter of fact the ruler of the Ottoman Empire Sultan Murat II had attacked Trabzon in 1442 from the sea and returned home taking slaves and taxes. Sultan Mehmet the Conqueror entered the citadel of Trabzon on Monday, the 26th of October 1461, he closed the phase of the Trabzon State that lasted 250 years in history. The Commander of the Fleet and the Governor of Gelibolu Kazim Bey took over the administration of the city.
Situated in a very beautiful and natural setting, Sumela Monastery built in the 14th century is nestled into the side of rocks in a famous valley in Macka, only 50 kilometers away from Trabzon. The setting is 1200 meters above the sea level.
St. Sophia Museum was built in covered Greek cross architecture during the reign of King Manuel I Kommenos in 13th century. Muslim Seljuk stone workers also worked for the construction of St. Sophia Church and church continued its service until 1670 after Ottomans invaded the region. It was converted into a mosque in 1670 and served as a storage and hospital during World War I. Later it served as a mosque again. The chapel in the north of the church is older and the bell tower and was built in 1427. St. Sophia Church was converted into a museum in 1964 and is located in 3 kilometers west of the city. It is not to be confused with St. Sophia Museum in Istanbul.