Within the sacred enclosure dedicated to Poseidon stands the Doric peripteral temple hexastyle of the god (460-390 BC). When the reconstruction of Corinth began in 44 BC, the various structures of the sanctuary of Isthmia were also renovated. The temple was rebuilt with the same dimensions of the cella, but it probably became an amphiprostyle temple, without outer rows of columns.
For more information about the history and archaeology of Isthmia see Isthmia in the Knowledge Center.