The medieval Kaleköy Castle has a stunning location on a peninsula hilltop across the water from Uçagiz. This is the site of ancient Simena, which dates from the 4th century BC.
The castle was built upon the foundations of the earlier Simena citadel and today, below the fortifications, you can still visit a seven-tiered 300-seat theater from this earlier settlement period.
There's also a necropolis just to the west, which contains mostly Roman sarcophagi in Lycian style.