Perge

This door, dating from the 2nd century B.C., was cleverly designed to protect the city, with it’s twin towers and a horseshoe-shaped courtyard at the back. It is thought that the towers were three tiered and were crowned by a conical roof. In the year 121 A.D. the courtyard was redesigned as a courtyard of honor. At the same time the forecourt was lined with columns, colored marble was placed on the walls into which niches were set to contain statues of the gods and the founders of the city. To the north of the courtyard was a triple triumphal arch.

— Taken from sign in city