Iassos was an ancient Greek city located in Caria on a small peninsula connected to the mainland by an isthmus. According to the historian Strabo, Iassos was well known for its fishing and had a harbour, making it an important commercial centre. Today, it is an extensive multi-period site located on the shores of the Gulf of Güllük, halfway between Didyma to the north and Halicarnassus to the south.

Coordinates: 37° 16′ 40″ N, 27° 35′ 11″ E

According to tradition, Iassos was colonised in the 9th or 8th century BC by Greeks from Argos (the Dorians). However, Archaeological evidence shows that the site had been inhabited since the Neolithic period and flourished as one of the major Minoan and Mycenaean settlements in Asia Minor. Prosperity continued throughout the Hellenistic, Roman, and Byzantine periods, with many of the remains visible today originating from these later eras.

Twentieth-century excavations have uncovered the Agora, dating back to the time of Hadrian and Antoninus Pius (AD 117 – 161), the bouleuterion (one of the best-preserved buildings in Iassos), temples, including a sanctuary dedicated to Artemis Astias (the patron goddess of the city), and numerous other buildings. Additionally, an impressive Roman-period funerary monument in the form of a Corinthian temple is located within the courtyard of the “Old Fish Market.” This site was restored in 1995 to serve as an open-air museum.