The medieval crusader castle above the present village of Kaleköy (Turkish for "castle village") was built on the remains of the ancient Lycian town of Simena by the Order of Knights of St John, who ruled Rhodes until 1522. The exact date of construction is not known. The castle walls with their swallowtail battlements are well preserved.

Kaleköy can still only be reached on foot or by boat. Some grave inscriptions and coin finds indicate that the place already existed in the 4th century BC.

In ancient times, Simena belonged to the Lycian League together with Aperlai, Apollonia and Isinda, but had never gained greater importance. Only a few ruins from antiquity have survived. Remains of the Titus thermal baths lie in the water today.
Also the necropolis with mostly Roman sarcophagi in Lycian style is partly sunken. A single sarcophagus rises freely out of the water, around it the remains of sunken paths can be seen.

Within the castle walls a small Lycian theatre carved into the rock has been preserved. Seven rows of seats offered space for about 300 people.