The ancient town of Perge was located on the right bank of the River Kestros (today known as Aksu) a few miles from its mouth. Small ships could reach the town directly from the sea. The first settlement was founded on a hill, but the town expanded into the plain where its main monuments were built. The main gate of Perge was protected by two round towers; they were built before the town became a Roman possession (188 BC). Later on with the expansion of Perge the towers lost their defensive purpose, but due to the elegance of their design they were retained and turned into a triumphal entrance to a long colonnaded street which crossed the town.