Corinth, Isthmus of, c.20 mi (32 km) long and 4–8 mi (6.4–12.9 km) wide, connecting central Greece (Attica and Boeotia) with the Peloponnesus, between the Gulf of Corinth and the Saronic Gulf. It is crossed by the Corinth Canal, built between 1881 and 1893, which connects the Aegean and the Adriatic seas. Parallel to the canal are ruins of the ancient Isthmian Wall, which was restored (3d–6th cent. A.D.) by Byzantine emperors to defend the Peloponnesus. Near the eastern end of the wall are ruins of the sanctuary of Poseidon where the Isthmian games were played.