In ancient Greek architecture, a propylaion, propylaeon or, in its Latinized form, propylaeum—often used in the plural forms propylaia or propylaea (/prɒpɪˈliːə/; Greek: προπύλαια)—is a monumental gateway. It serves as a partition, separating the secular and religious parts of a city. The prototypical Greek example is the propylaea that served as the entrance to the Acropolis of Athens. The Greek Revival Brandenburg Gate of Berlin and the Propylaea in Munich both evoke the central portion of the Athens Propylaea.