The ancient city was founded during Archaic Period, but some people think that it already existed since the Late Geometric period. On the 4th century B.C, ancient Stymphalia was built in the northern side of the lake, where today you can find its ruins. A big part of the ancient city is half-submerged into the lake and only a part of the stadium of the later Hellenistic period is on the surface.
Excavation brought into the light some wreckage of public building of the ancient agora, structures of palaestra, tunnel, one of the three clepsydras in Greece, etc. The houses were built east and north of the acropolis.
