Iasos was founded by the colonists of Argos, and later came under the control of Miletus. In the 5th century B.C., Iasos was a member of the Attica-Delos confederation. Many of the citizens of Iasos earned their livings by fishing, which is still true today. Apollo and Artemis were the protector deities.

Like other settlements in the region, Iasos was destroyed by the Persians. It was rebuilt during the era of Alexander the Great, and then the city was taken by Alexander of Macedonia. Gorgos of Iasos was one of this Alexander’s leading commanders. He convinced the ruler to reinstate fishing activity under his brother in the city. The appreciative citizens of Iasos erected their statues in the theatre, and exempted Gorgos and his brother from paying taxes for the rest of their lives.

For boys who spent their days training day in the gymnasium at Iasos, bathing in the sea was a tradition. One day while the boys were bathing, according to legend, a dolphin continuously took one boy away and then brought him back. Alexander the Great made that boy a priest in Babil. Another legend says that the boy cut himself while he was playing with the dolphin, and the dolphin took the dead boy to shore and died on the beach beside him. Local coins with a boy on a dolphin date from the 3rd century B.C.

In addition to the well-preserved agora, the theatre dating from the 4th century B.C., the bouleterion, the temple of Artemis, the fish market, and a funerary monument in the form of a Corinthian temple are the most impressive ruins from the Roman period.