The South part of the Agora (The North part lies in the Eastern Archaeological area) is dominated by two monuments, the stone-built temple of the Attalids and the altar of Dionysos, that were revealed during the Italian Archaeological Service excavations in 1933, under the direction of L. Laurenzi.
The temple of the Attalids, with a North-South alignment, dates from the first half of the 2nd century BC and continued to be in use until the Roman Imperial period, when large scale remodelings were carried out.
Only the foundation of the stepped podium is preserved from the Hellenistic temple, built of ignimbrite rock, along with sporadic parts from its facade of hard grey limestone. Although no architectural parts of the temple have been found, scholars have reconstructed it as a distyle in-antis temple of Ionic order, or a tetrastyle prostyle temple of Doric order.
Stone-built pedestals, probably meant for votive offerings, are preserved around the temple. A colossal statue depicting a thorakophoros (male figure wearing a cuirass), with his himation wrapped around his waist, was found in its vicinity. Two shields of Gallic type are carved in relief on the strut of the statue. The statue has been identified as King Eumenes II of Pergamon (197-158 BC), who was honoured by the Koans on the occasion of his first victory against the Gauls in 183 BC. The organised cult of Eumenes in Kos, confirmed from epigraphic evidence, is attributed to the particularly close relations established by the two states of Kos and Pergamon during that period. It is believed that the statue of the victorious king stood in the pronaos (anteroom) of the temple and that he was worshipped as synnaos (temple-sharing) with another deity, probably Dionysos, founder of the House of the Attalids.