Proof of visual skills

 Do please  guess in less than 5 seconds, which is the city we are talking about:

X is the center of the historical world. The circle with the smallest radius that can be drawn from any center on the globe to include the ten most influential cities in history, Athens, Istanbul, Antioch, Damascus, Baghdad, Jerusalem, Alexandria, Cairo, Mecca and Beirut, is the circle that has X as its center.

Solution and key, here.