The Corinth Canal connects the Gulf of Corinth with the Saronic Gulf in the Aegean Sea. It cuts through the narrow Isthmus of Corinth and separates the Peloponnese from the Greek mainland, arguably making the peninsula an island. The canal was dug through the Isthmus at sea level and has no locks. It is 6.4 kilometres (4 mi) in length and only 21.4 metres (70 ft) wide at its base, making it impassable for most modern ships. Nowadays it has little economic importance and is mainly a tourist attraction.

Corinth was a city-state on the Isthmus of Corinth, the narrow stretch of land that joins the Peloponnese to the mainland of Greece, roughly halfway between Athens and Sparta.Since 1896, systematic archaeological investigations of the Corinth Excavations by the American School of Classical Studies at Athens have revealed large parts of the ancient city, and recent excavations conducted by the Greek Ministry of Culture have brought to light important new facets of antiquity. For Christians, Corinth is well known from the two letters of Saint Paul in the New Testament, First and Second Corinthians. Corinth is also mentioned in the Acts of the Apostles as part of the Paul the Apostle's missionary travels.Ancient Corinth was one of the largest and most important cities of Greece, with a population of 90,000 in 400 BC.The Romans demolished Corinth in 146 BC, built a new city in its place in 44 BC, and later made it the provincial capital of Greece.

Acrocorinth, "Upper Corinth", the acropolis of ancient Corinth, is a monolithic rock overseeing the ancient city of Corinth, Greece. In the estimation of George Forrest, “It is the most impressive of the acropoleis of mainland Greece.With its secure water supply, Acrocorinth's fortress was repeatedly used as a last line of defense in southern Greece because it commanded the Isthmus of Corinth, repelling foes from entry by land into the Peloponnese peninsula. Currently, it is one of the most important medieval castle sites of Greece.