The fortification of Chios dates from the ancient times, however the castle was constructed between the 7th and 9th century BC in order to defend the enclosed population and properties against naval attack and siege.
Ever since, the place has been the political, financial and social center of the island, while historic events determined its final form. Being the walled core of the town, the astounding fortress of the Medieval Civitas Chii enchanted visitors from the east and the west.
Its walls create an irregular pentagon. With a perimeter of 1.100m, the castle occupies 77 acres comprised mainly of bastions, rampart and towers.
There is evidence that the South side of the castle, the one adjacent to the port, was constructed in the 19th century, during the construction of the port. Its terrestrial walls, surrounded by a moat, have three different entrance gates, two accessible from land and one from the sea.
Its main entrance (porta Maggiore) is at the South end. There is another entrance at the NorthWest side (Portello) and finally porta di Marina at the Southwest end of the sea-side wall.
The unique architectural heritage of the castle and the settlement, is further enhanced with the restoration of the Byzantine Baths, the main square within, the stone bridge leading to the main entrance – porta Maggiore- and the recently restored sea-side wall.