:For the Microsoft application framework, see Microsoft codename "Acropolis". Acropolis (Gr. acro, high + polis, city, pl. acropoleis) literally means a high city. For purposes of defense, early settlers naturally chose elevated ground, frequently a hill with precipitous sides, and these early citadels became in many parts of the world the nuclei of large cities which grew up on the surrounding lower ground, or modern Rome.

The word "Acropolis", though Greek in origin and associated primarily with Greek cities (Athens, Argos, Thebes, and Corinth with its Acrocorinth), may be applied generically to all such citadels (Rome, Jerusalem, Celtic Bratislava, many in Asia Minor, or even Castle Rock in Edinburgh) The most noted example is the Acropolis of Athens which, by reason of its historical associations and the several famous buildings erected upon it (most notably the Parthenon), is generally known without qualification as simply "The Acropolis". Although originating in the mainland of Greece, use of the acropolis quickly spread to Greek colonies such as the Dorian Lato on Crete during the Archaic Period.

Because of its classical Greco-Roman style, the ruins of Mission San Juan Capistrano's "Great Stone Church" (in California, United States) has been dubbed the "American Acropolis".

Other parts of the world developed other names for the high citadel or alcázar, which often reinforced a naturally strong site. In Central Italy, many small rural communes still cluster at the base of a fortified habitation known as "La Rocca" of the commune.

The term acropolis is also used to describe the central complex of overlapping structures, such as plazas and pyramids, in many Mayan cities, including Tikal and Copán.