Isthmus of Corinth

The Isthmus of Corinth, a narrow strip of land near the city of Corinth, links the Peloponnese peninsula to the Greek mainland. At just 6.3 kilometers (3.9 miles) wide, it served in antiquity as the boundary between the Peloponnese and the rest of Greece. In the first century AD, the geographer Strabo recorded a stone marker on the isthmus bearing two inscriptions: one facing east toward Megara read, “Here is not Peloponnesus, but Ionia,” while the one facing west toward the Peloponnese read, “Here is Peloponnesus, not Ionia.” Plutarch attributed this stele to the Athenian hero Theseus, who supposedly set it up on his journey to Athens. To the west lies the Gulf of Corinth, and to the east the Saronic Gulf. Since 1893, the Corinth Canal has cut through the isthmus, effectively turning the Peloponnese into an island. Today, two road bridges, two railway bridges, and two submersible bridges at each end of the canal connect the mainland side to the Peloponnese, with a military emergency bridge also located at the canal’s western end.

The idea of a canal to spare ships the long voyage around the Peloponnese was considered by the ancient Greeks. The tyrant Periander first attempted to build one in the 7th century BC but abandoned it due to technical challenges, instead constructing a simpler stone portage road called the Diolkos, whose remnants still exist near the modern canal. Under Roman rule, various solutions were tried. Julius Caesar saw the value of a link for his new colony, Colonia Laus Iulia Corinthiensis. During the reign of Tiberius, engineers tried digging a canal but were thwarted by a lack of modern equipment; they then adopted an ancient Egyptian method, rolling ships across the isthmus on logs, a practice in use by AD 32. In AD 67, the philhellene emperor Nero ordered 6,000 slaves—whom historian Flavius Josephus identified as Jewish pirates captured by Vespasian—to dig a canal with spades. According to Pliny the Elder, the work advanced about four stadia (roughly 0.8 kilometers). Nero died the following year, and his successor Galba halted the project as too costly. In modern times, the idea was seriously proposed in 1830, shortly after Greek independence from the Ottoman Empire, and was completed in 1893 after eleven years of work.

Near the canal runs the ancient stone trackway known as the Diolkos, once used for dragging ships overland. There is significant concern over its preservation, with Greek campaigners urging the government to do more to protect this archaeological site. Also located close to the canal is the Hexamilion wall, a Roman defensive barrier built across the isthmus to guard the only land route into the Peloponnese; it is the largest single archaeological structure in Greece.