The Theater

 theatre, ruins, archaeological site

First built at the end of the 5th century BC, the theater was designed to accommodate around 500 spectators. Drama and musical events played an important role in the Isthmian games; these competitions were just as important as the athletic events. The theater was remodeled by the Romans in AD 67 for the emperor Nero's visit to the Isthmian games. It was eventually abandoned in the latter 3rd century. Today, spolia from the theatre can be found in the hexamilion wall.

An additional interesting feature near the theater is the location of the "cult caves." Positioned above the seating area there is a cave, divided into two chambers. Large amounts of dining ware, plates, and pans were found in this area, suggesting that ceremonial feasting was a part of the cult's activities. More than likely, worshipers in this ancient cult would have gathered to share common meals together. Poseidon, Palaimon, or Dionysus have been suggested as the primary deity for the cult activity in these caves. The cult caves were out of use by the late 4th century BC.

from:
isthmia.osu.edu/features.html