The city on the Black Sea which might serve as a crossroad between Europe and Asia is Istanbul, Turkey. It is because it is the only city which stands on two continents – that of Europe and Asia through the Bosporus Strait which connect the Black Sea and the Sea of Marmara. Its strategic location serves as the central area to the trade routes in different places such as Europe, Horn of Africa, the Arabian Peninsula, Iran, Caucasus, the Balkans, the Mediterranean Basin and the Russian steppe.
Istanbul was historically known as Constantinople and Byzantium with an urban and rural area of 1,539 square kilometers and 5,343 square kilometers respectively, and a combined total population of more than 14 million people.