Several architectural phases are distinguished in the fortification walls of Naupactos, dated from the Greek antiquity until the Turkish occupation.
The castle is built on the site of the ancient acropolis. Naupactos was destroyed by an earthquake in A.D.553 and from the 8th century on, it became the capital of the fifth Theme of Byzantium. It remained under Greek control until 1204, when it was given away to the Venetians. In 1210, Michael Angelos Comnenos included the city in the properties of the Despotate of Epiros. In 1294 it came under the control of Philip d'Anjou and in 1360 was conquered by the Albanian leader, Ghino Buo Spata. From 1407 until 1444 the Turks, who kept it until 1687, occupied it by the Venetians and then. From 1687 until 1699 it was again under the Venetian control and remained under Turkish domination until 1829.