Being the most important trade center of Ephesus, Agora was built in the third century B.C in the Hellenistic Period, but the ruins date from the reign of Caracalla (211-217 C.E)

It is in the form of a square, each side 110 meters, and surrounded completely by columns. The Agora has 3 gates, one from the front of the theatre on the northeast, the other one opening to the harbor on the west and the third one from the Celsius Library. The north side of the Agora is left open, and the other three sides are surrounded by a portico, in which there are rows of shops. At the center of the Agora was a sundial and a water-clock.