defensible hilltop used as a settlement's religious, military, and/or political center

The word acropolis (Greek: acron, edge + polis, city) means the edge of a town, or more often a high city. Being easily defended against attackers, an acropolis often has a citadel. The most famous is the Acropolis of Athens.

"Acropolis" is also used for a central complex of overlapping structures, such as plazas and pyramids, in many Mayan cities, including Tikal and Copán.