Although it looks like this from below, the Acropolis of Kaunos is not a castle in the classical sense. It lies on a steep limestone rock, 152 meters above the city. From here, the city, including the harbour entrance and large parts of the swamp area and today the almost silted up delta of the river-like inflow of today's DalyanÇayı, a navigable canal to Lake Köyceğiz, was easy to overlook.

The terrain below the summit is divided into three large terraces, the largest of which surrounds the summit on all 4 sides. It is assumed and supported by finds that it was used as a sacred place in archaic times, but that it was also a fortified retreat for the inhabitants of Kaunos in times of danger. There is much to suggest that the site is the sanctuary of Zeus, referred to in inscriptions.

The walls visible today from the ruins of the city, such as the Roman bath or the theatre, date back to the Byzantine period and at the same time represent the last phase of the extension of the Acropolis fortification. The walls, which run about 35 metres below the summit, date from the archaic period (750 - 475 BC) as well as the Hellenistic period (323 BC - 30 BC) and can be identified by distinguishing the building techniques used. They were repaired several times and were strengthened and extended again and again in the subsequent period.

Kaunos was only of secondary importance in Byzantine times due to the silting up of the harbour and the malaria-contaminated and marshy delta. In Ottoman times it had become a fishing village with a small garrison, but in the first half of the 18th century it almost completely became an abandoned ruined town.