The Agora was founded in the 3rd cent. BC, to the east of the theatre, in contact with the Arsinoe fountain. It covers an area of 40,000 square meters, surrounded by four stoas, one on each side. The buildings in the Agora were used to house the city’s financial, political and religious functions. Such were the earlier Bouleuterion, the Prytaneion, the Kreopolion (meat market) and the north stoa. The market inspectors’ tables have been preserved, with hollows for measuring grain and liquids.

The temple of the mythical queen Messana was built in the middle of the Agora. An underground chamber south of the temple was used as a treasury. The general Philopoimen from Megalopolis was imprisoned and put to death in this chamber in 183 BC. Pausanias mentions the statue of Zeus Soter, sanctuaries of Poseidon and Aphrodite and a statue of the Mother of Gods (Cybele), a work of the sculptor Damophon.