Famous Istanbul historian Jak Deleon writes about Istanbul in his book named 'The Bosphorus: A Historical Guide ' :

''From Byzantium to Constantinople and from then to Istanbul, this fabled city, divided by the Bosphorus strait, lies in both Europe and Asia. The European side is seperated into two by a scimitar-shaped gulf called the Golden Horn: the old town sprawls along one side, with its Byzantine ramparts and Ottoman palaces facing the Marmara Sea, the Propontis of antiquity; on the other side, one can see the ancient Genoese port of Galata and the more modern quarters beyond, with the legendary Bosphorus winding its way up to the Black Sea, the Pontus Euxinus of antiquity. It is this garland of waters which makes Istanbul, whose seven hills are crowned with imperial monuments, a unique city.

The legend of the foundation of Istanbul is derived from classical mythology: Zeus fell in love with Io, the daughter of Inachus, King of the City of Argos and God of the River of Argos.The King of the Gods temporarily transformed his beloved daughter into a heifer in order to protect her from the wrath of his wife, Hera, Queen of the Gods. In her wanderings Io crossed the Bosphorus, giving the strait its name (''boos-foros'',''cow-ford''). After reassuming her original form, she gave birth to a girl, Keroessa. Later, Keroessa bore the son of Poseidon, grandson of Gaea ( Mother Earth ) and Uranus ( Father Sky ), son of Cronus, elder brother of Zeus and sovereign deity of all waters from the Pillars of Hercules to the Hellespont. Keroessa's son, Byzas the Magerian, in time became the founder of Byzantium and named the Golden Horn ( Chrysokeras ) after his mother.

Following the advice of the Oracle of Apollo at Delphi, Byzas established a colony at the tip of the Istanbul peninsula, today known as the Seraglio Point, the Promentorium Bosphorium of antiquity, where the Bosphorus and the Golden Horn meet and flow into the Marmara ( 667 B.C. ). Almost a millenium later, during the era of the Roman Emperor Constantinus, Byzantium was renamed Constantinople ( 330 A.D. ). When captured by Mehmet the Conqueror, the city became the capital of the Ottoman Empire assuming its present name, Istanbul ( 1453 A.D. ).

Istanbul was besieged numerous times over the centuries by Persians, Macedonians, Lombards, Slavs, Avars, Bulgarians, Russians, Goths, Huns, Pechenegs, Crusaders and Islamic armies. Five Arab campaigns are mentioned in the chronicles:

1. The Arab fleet, commanded by Abdullah Ebu Serh, defeated the Byzantine navy off the coast of Phoenix ( Fenike ) in southwestern Anatolia, but could not reach Istanbul (655 A.D.).

2. Under the command of Halid bin Zeyd Ebu Eyyub el-Ensari, the Arabs surrounded the city by land. Halid bin Zeyd Ebu Eyyub el-Ensari was the ''Sancakdar'' ( Standard Bearer ) of the Prophet Muhammed; he was also known as ''Mihmandar-i Resulullah'' ( Host of the Prophet ). He fell as his forces attempted to conquer Istanbul. Eventually, the siege had to be lifted ( 668 A.D. ).

3. The Arab navy attacked Istanbul and held fast for seven years ( 674-680 A.D. ).

4. During the reign of Caliph Suleyman bin Abdulmelik, Arab armies under the command of Mesleme bin Abdulmelik and Abdullah bin Tayyib besieged Istanbul both by land and sea, advancing as far as the chain at the entrance of the Golden Horn. The fighting along the ramparts was fierce and the Arabs finally withdrew, recalled by Caliph Omer bin Abdulaziz, successor to Suleyman bin Abdulmelik. ( 715 A.D. ).

5. The final Arab conquest to capture Istanbul took place under the command of Harun-ur Rashid. The Arab army advanced as far as Chrysopolis ( Uskudar ) on the Asian shore of the Bosphorus and eventually forced the Byzantines to sign a treaty ( 782 A.D. ).

The seven sieges of Istanbul recounted in Ottoman history date as far back as the 14th century A.D.:

1. Ottoman Sultan Yildirim Beyazid besieged the city for seven months. The siege was altered to form a blockade as the sudden threat of a Hungarian attack emerged. The Byzantines, however, accepted certain conditions which included the creation of a Turkish quarter within the city, the establishment of a Turkish court with a judge appointed by the Ottoman Sultan, the construction of a mosque and the foundation of a Turkish garrison on the northern shores of the Golden Horn. In addition, the Ottomans would receive an annual tribute of 10.000 gold pieces ( 1391 A.D. ).

2. The Byzantines refused to accept some of the conditions put forth in 1391, and Yildirim Beyazid's army surrounded Istanbul once more. As the blockade turned into a siege, news reached the Sultan that the Crusaders were marching towards the Balkans. Yildirim Beyazid lifted the siege and led his troops into the Balkans to confront the Crusaders ( 1395 A.D. ).

3. Having defeated the Crusaders, Yildirim Beyazid once more turned his attention to Istanbul. In order to prevent military help from reaching the Byzantines via the Black Sea, he had the Anatolian Fortress ( Anadolu Hisari ) constructed at the narrowest point of the Bosphorus on the Asian side. Finally the Byzantines accepted all the conditions laid out in the siege of 1391. The annual tribute was raised to 30.000 gold pieces ( 1397 A.D. ).

4. The Ottomans' conditions were weighing heavily upon the Byzantine Emperor's offers and he asked the Crusaders for assistance. Having received this news, Yildirim Beyazid immediately surrounded Istanbul. The city almost fell under heavy cannon fire when Timur, the Mongolian King, began sacking Eastern Anatolia. Once more, the Ottoman Sultan had to divert his army away from Byzantium.

5. The feud between the two heirs to the Ottoman throne, Prince Musa and Prince Mehmet, served not only to weaken the Ottoman Empire but to further strengthen Byzantium's position. As Prince Musa besieged Istanbul, Prince Mehmet attacked his brother's forces. Thus, the siege had to be lifted ( 1412 A.D. ).

6. Murat II laid a siege the moment he ascended the Ottoman throne. Just as Byzantine resistance was broken and Istanbul had almost capitulated, a major rebellion broke out in Anatolia, started by a pretender to the Ottoman throne, Sultan Murat's younger brother, Prince Mustafa. Once more, as brother marched against brother, the Byzantines were left to their own devices ( 1422 A.D. ).

7. The seventh and final siege of Istanbul was carried out under the command of Mehmed II, the Ottoman Sultan historically known as Mehmet the Conqueror. Mehmet the Conqueror had the Rumeli Fortress ( Rumeli Hisari ) constructed on the European shore of the Bosphorus, directly across from the Anatolia Fortress, thus cutting off all Black Sea traffic in and out of the city. Nevertheless, Cardinal Isidore of Kiev, the Pope's envoy, arrived in Istanbul to seal the union between the Catholic and Orthodox Churches. This union, proclaimed by Constantinus in Haghia Sophia ( the Church of Holy Wisdom ), caused unrest among the devoutly Orthodox Byzantines, and popular opinion swayed strongly against the Emperor. Meanwhile, Mehmet the Conqueror moved his galleons over the land by means of specially constructed sleds and pulleys and the Byzantines woke up one morning to find the Golden Horn invaded by the Ottoman navy. Enormous shell-holes were torn in the ramparts through which the Sultan's soldiers entered the city and, by means of a temporary bridge built across the Golden Horn, they crossed into the heart of Genoese Galata. The entire battle took place between April 6 and May 29, and on this final day, Istanbul, once the capital of the Byzantine Empire, fell to the Turks. Mehmet the Conqueror, Sultan of the Ottoman Empire, was 21 years old and the city was 2120 years old ( 1453 A.D. ). ''