Acropolis (Greek akros, “highest”; polis, “city”), fortified natural stronghold or citadel in ancient Greece. The Greeks built their towns in plains near or around a rocky hill that could easily be fortified and defended. The word acropolis referred both to the hill and to what was built on it. Almost every Greek city had its acropolis, which provided a place of refuge for townspeople during times of war. Sometimes the ruler of the town lived within the walls of this stronghold. In many cases the acropolis became the site of temples and public buildings and thus served as the town’s religious center and the focal point of its public life and as a place of refuge.