Acropolis means "high city" in Greek or citadel. For purposes of defense, early people naturally chose elevated ground to build a new settlement, frequently a hill with precipitous sides. In many parts of the world, these early citadels became the nuclei of large cities, which grew up on the surrounding lower ground, such as modern Rome. (From Wikipedia) Acropolis is usually made of white marble, so that acropolis will not fall easily. Therefore, acropolis is a shade of white and somehow a little tint of black.
Acropolis in Greece