isthmus dividing the Saronic Gulf (an inlet of the Aegean Sea) from the Gulf of Corinth (an inlet of the Ionian Sea). The Isthmus of Corinth connects the Peloponnese with mainland Greece. It is made up of heavily faulted limestone rising from the south in terraces to a bleak, windswept central plateau almost 300 feet (90 m) above sea level. In ancient times ships were dragged over the isthmus in transit between the Saronic and Corinthian gulfs, and in AD 67 the Roman emperor Nero began a canal through it. In 1893 a 3.9-mile (6.3-kilometre) ship canal, the Corinth Canal, was opened that shortened the journey from the Adriatic Sea to Athens' port, Piraeus, by more than 200 miles (320 km). To the south is the site of the Isthmian sanctuary at which the biennial Isthmian Games were celebrated in antiquity.