This work presents a history of the Greek city of Byzantium centuries before it became the imperial capital as Constantinople. The discussion considers the merits of its position with respect to the Bosphorus Canal but also the repeated difficulties in defending a productive city territory from external interferences, especially non-hellenic ones. Great attention is paid to the constants and long-term phenomena, in particular to the network of interstate relations that Byzantium was able to build both in the Straits and Black Sea area and in the Aegean Sea.