Isthmia is an ancient sanctuary of Poseidon and important archaeological site and museum located on the Isthmus of Corinth in Greece.

Small samples of pottery dating to the last era of the Bronze Age (1600-1200 BC) show that people were still living in Isthmia during this time.

In 390 BC, during the Corinthian War, the Spartan king Agesilaus encamped at the sanctuary and the archaic temple of Poseidon was burned down in uncertain circumstances.

[2] The lack of pottery found at the site after the fire indicates that Isthmia entered a period of decreased prosperity at this time.

[3] After Philip II, King of Macedon won the Battle of Chaeronea in 338 BC, he united the Greek city-states into the League of Corinth, which was formed at a council at Isthmia.

[2] In 146 BC, rising tensions between the Greek states and the increasingly hegemonic Romans resulted in a last attempt by the Achaean League to maintain its independence.

The Achaean War ended in a quick Roman victory, and consul Lucius Mummius Achaicus ordered the complete destruction of Corinth as an example to all Greeks.

[2] The Emperor Nero visited the site on his tour of Greece in AD 67 and performed in the musical events at the Isthmian Games.

[2] The Temple of Poseidon fell into disuse and its material was partly re-used for the building of the Hexamilion wall which was used as protection against invading barbarians in the 5th century.

In 1715, the Venetians were expelled, and the Ottoman Empire controlled southern Greece for a hundred years until the Greek War of Independence.

[8] Between August 16 and November 29, 1989, she led new excavations in the central area of the sanctuary under the auspices of the University of Chicago, mostly to clear up disputes that had arisen over the conclusions Broneer had drawn from his finds.

These excavations helped to uncover evidence relating to all the areas of development of Isthmia from the Bronze Age to the Roman period, but in particular focused on the Archaic temple, partly because this is the most complete of the buildings found at the site despite being one of the oldest.

A multitude of other named divinities said to have been worshipped within the confines of the temple have links to Demeter, suggesting the Isthmian people's devotion to fertility and harvest.

According to Timothy E. Gregory, this is the largest monochrome mosaic excavated in the eastern Mediterranean and is one of the most important works of art found at Isthmia.

[16] The mosaic is divided into 3 sections, with two containing geometric designs and one showing similar images of Greek Tritons carrying Nereids on their backs.

Excavations led by Elizabeth Gebhard and Oscar Broneer in 1959, 1960, and 1967 found evidence for a structure that was built in the classical period and was renovated at several later points in time.

[17] Following a lengthy period of abandonment of the site, a new phase of the theater began at the end of the 1st century A.D. when control of the sanctuary had passed to the Romans.

The water channel surrounded the outer perimeter of the running track and flowed through two basins on opposite sides of the starting line.

A series of straight shallow grooves extend from these sockets to a single round cutting at the apex of the pavement that served as the starter’s position.

The upright posts held a horizontal piece of wood attached to a string, which could be manipulated to swing down to vertical at the desire of the starter.

This unique system may not have functioned as intended and was quickly replaced by more practical starting methods that relied on a single barrier stretched in front of all the runners.

[18]The water channels that flank the track are lined with hard stucco material, and shows the change of influence from Greek to Roman as parts were added.

[18] On the eastern side of the temple there is a field with excavated remains of small buildings, most likely houses, that had water facilities and food preparation areas.

Beginning in the late 8th century, evidence of a more defined sanctuary space is made with the construction of an altar and Temenos walls.

The bodies have been dated to come from different time periods and are spread throughout the areas of excavation, suggesting that habitation in Isthmia was widespread and deep-rooted.