The isthmus is where the Peloponnese begins. Were it not for this narrow neck of land less than 7 km (4½ miles) across, the waters of the Gulf of Corinth and the Saronic Gulf would meet and would make the Peloponnese an island; hence the name, which means "Pelops's island."
For the ancient Greeks the isthmus was strategically important for both trade and defense; Corinth, with harbors on either side of the isthmus, grew wealthy on the lucrative east–west trade. Ships en route from Italy and the Adriatic to the Aegean had to sail around the Peloponnese, so in the 7th century BC a paved roadway called the Diolkos was constructed across the isthmus, over which ships were hauled using rollers. You can still see remnants near the bridge at the western end of the modern canal.
West of the isthmus, the countryside opens up into a low-lying coastal plain around the head of the Gulf of Corinth. Modern Corinth, near the coast about 8 km (5 miles) north of the turnoff for the ancient town, is a regional center of some 23,000 inhabitants. Concrete pier-and-slab is the preferred architectural style, and the city seems to be under a seismic curse: periodic earthquakes knock the buildings down before they have time to develop any character. Corinth was founded in 1858 after one of these quakes leveled the old village at the ancient site; another flattened the new town in 1928; and a third in 1981 destroyed many buildings. Most tourists tend to avoid the town altogether, visiting the ruins of Ancient Corinth and moving on.