Antiphellos Antique City is one of the most important historical ruins of Kas.

The ancient theater, located in the ruins of the ancient city, has survived to the present day in a very complete and robust state. The theater has a capacity of 4000 people and was built in the 1st century BC and repaired in the 2nd century BC.

The theater is very close to the sea as of its location. The unique feature of the structure is that it is the only theater with its façade towards the sea among the ancient theaters in Anatolia.

The ancient theater, which is a 5-minute walk from the center of Kas, is sometimes used for various art events.

Near the theater, there is a 4th century BC house-shaped tomb in dor style called Akdam. This structure was built by cutting a natural rock. The height of the building is 3.5 meters and there are girl figures dancing on the inner walls. In addition, there is a temple in the ancient city, built on cut stone, on Hospital Street. It was determined that the stones used in the foundation of the temple were built during the Roman Period.

There is also a water cistern at the entrance to the marina. This cistern has survived from the Lycian period.