The Ancient Market was built in the 4th century BC. and it was the commercial and social center of Kos. It is a short distance from the port of the city and is one of the largest ancient markets that have been excavated to date in Greece.
As an archaeological site, the market is part of the wider archaeological zone of the harbor, the now visible section of which covers an area of 152 m in length and 82 m. latitudinal. In this zone, apart from the visible segment of the market, visible part of the fortification of the city, the sanctuaries of Aphrodite and Herakles, building islands with the remains of private houses, as well as part of the ancient port of the city.
Most of the ancient market is buried under the modern city. In fact, its southern part came to light with recent excavations opposite the altar of Dionysus, which led to the restoration of two columns belonging to the ancient market.