An acropolis (; from akros or akron, "highest", "topmost", "outermost" and polis, "city"; plural in English: acropoles, acropoleis or acropolises) is a settlement, especially a citadel, built upon an area of elevated ground—frequently a hill with precipitous sides, chosen for purposes of defense. In many parts of the world, acropoleis became the nuclei of large cities of classical antiquity, such as ancient Rome, and for this reason they are sometimes prominent landmarks in modern cities with ancient pasts, such as modern Rome.