Corinth's power was always geographic. The Isthmus of Corinth — barely 6.4 kilometers across at its narrowest — is the only land route connecting mainland Greece with the Peloponnese. Ships sailing between the Ionian and Aegean worlds faced a choice: brave the treacherous waters around Cape Malea at the southern tip of the Peloponnese, or pay Corinth's tolls and use its land crossing. Most paid the tolls. The city collected fees on goods portaged overland, and grew rich. By the 8th century BC, Corinth was already developing as a commercial center, and its position between two great gulfs — the Gulf of Corinth to the northwest and the Saronic Gulf to the southeast — made it essentially a tax on Mediterranean trade. Its harbors at Lechaion and Cenchreae served both coasts. Towering over it all was the Acrocorinth, a great monolithic rock rising 575 meters above the coastal plain, offering a fortress that could see the sea on both sides.

The site was occupied before 3000 BC, but the historical record sharpens in the early 8th century. The Bacchiad clan ruled for generations before Cypselus overthrew them, and between 657 and 585 BC, Cypselus and his son Periander ruled as tyrants — a word that in archaic Greece simply meant a ruler who came to power outside traditional channels, not necessarily a cruel one. Periander in particular was counted among the Seven Sages of Greece, even as his reign mixed brilliance with violence. After the tyrants came oligarchy, then alliance with Sparta in the Peloponnesian League. Corinth fought alongside Sparta against Persia and then Athens, then fell out with Sparta after their shared victory, pursuing its own course through the shifting alliances of the 4th century. When Macedon conquered Greece, Acrocorinth became the garrison of a Macedonian occupying force — the "fetters of Greece," as ancient writers called the Macedonian strongholds — until 243 BC, when Corinth joined the Achaean League.

The Roman destruction of 146 BC was deliberate and total. Mummius did not merely defeat Corinth; he erased it, killing its men and selling its women and children into slavery. The event shocked the Greek world. Ancient sources describe the plunder of artworks and the systematic dismantling of a civilization. For over a century the site sat as a kind of warning, managed as Roman public land by squatters and temporary workers. Then Caesar intervened. In 44 BC, he refounded the city as Colonia Laus Iulia Corinthiensis, settling it with 16,000 colonists — Roman freedmen, veterans, and members of the extended Julian family. The geography that had made the old Corinth rich made the new one rich too. The Roman city was laid out on a grid, with a forum replacing the old Greek agora. The Lechaion Road became the cardo maximus, the great north-south spine, still traceable in the excavations today. Corinth became the capital of the Roman province of Achaea.

Wealth attracted religion, and Corinth attracted everyone. The Apostle Paul arrived during his second missionary journey, around AD 50, during the reign of Emperor Claudius. He stayed for eighteen months — an unusually long residence — preaching in a city that was cosmopolitan, noisy, and commercially minded in the way that port cities tend to be. Near the Lechaion Road, archaeologists found a limestone lintel inscribed in Greek: [SYNA]GOGE EBR[AION] — "Synagogue of the Hebrews" — evidence of the Jewish community Paul would have found here. A separate paving stone, the Erastus Inscription, names "Erastus, the Aedile," and an Erastus appears in Paul's letter to the Romans, written from Corinth, illustrating how early Christianity intersected with the city's governing class. The letters Paul wrote to the Corinthians speak to a community that was prosperous, fractious, and deeply embedded in the social world of a Roman trade hub.

Corinth's long history is also a history of destruction by forces other than armies. In 856 CE a major earthquake struck the region, causing an estimated 45,000 deaths. In 1858, a magnitude 6.5 earthquake destroyed the settlement that had grown up around the ancient ruins, prompting the founding of New Corinth on the Gulf coast. In 1928, a magnitude 6.3 earthquake devastated that city, which was rebuilt in place. In 1933, fire added another layer of ruin. The Corinth that exists today — a city of about 30,000 on the shore of the Gulf of Corinth, the capital of the Corinthia regional unit — is the product of all this destruction and rebuilding, a modern city layered over ancient rubble, with the old ruins of Greek and Roman Corinth a few kilometers to the southwest and the great rock of Acrocorinth standing watch over both.