The castle of Chios is one of the largest castles in Greece, having an area of 180,000 square meters. It is located on the north side of the port. According to excavations it has been found that the castle existed during the Byzantine period and specifically during the 10th century. The present form of the fortress is mainly characteristic of the time of the Genoese, as it was rebuilt in the 14th century by the ruler of the island Martino Zaccaria. In the Middle Ages the castle was the center of the political and military administration of Chios. Pial Pasha occupied the fortress in 1566 on behalf of the Ottoman Sultan Suleiman the Magnificent. In 1694, for half a year, Venetians occupied the castle and made repairs to its fortifications despite the short period of their rule. Until 1912 when the island was liberated and incorporated into the Greek state it was in the hands of the Ottomans.
Despite the major disasters suffered by the earthquake, it continues to inhabited until today.