Rio Castle Fortification, built opposite to the castle of Antirrio to control the sea passage from the Ionian Sea to the Gulf of Corinth, called Küçük Tsanak Kale, ie Small Dardanelles. In 1499 was built the first fortification of the pass by Bayazid II, smaller in size with a double circuit and a moat. In 1532 it was conquest by the Spaniards and Andrea Doria, and retaken by the Turks. In 1603, the Knights of Malta brought significant destruction. In 1687 it was taken by Morosini. Drastic repairs of the castle will give the form it has today: new towers-bastions and strengthened ramparts. At the same time was constructed the picturesque church of Zoodochos Pigi, still in use for ceremonies. In 1715 the castle was taken by the Turks, and in 1828 the castle after a siege by the Turks was given to General Maison. Then it is repaired and delivered to the Greeks. The castle was used as a prison for a long time. In World War II Germans settled into it.