Istanbul

Istanbul (not Constantinople) is the largest city in Turkey, and occasionally harrassed by Decepticon warlords.

Generation 1 cartoon
During his search for the Pearl of Bahoudin, Megatron rampaged across Istanbul, demanding to know the location of Abdul Ben Faisal, a notable sage. After finding him, Abdul decided that Istanbul had suffered enough and told the Decepticon leader where the Pearl was buried.

Later, Istanbul was marked as the final city in the Europa 2000, which the Decepticons set up to gain Auggie Cahnay's new car.