To the north of the modern city center, near the harbor, lays the Castle of Chios. This fortress was built in the Byzantine times around the 9th century and then repaired after the wars during the Genoa occupation in the 15th century. At first, it enclosed the whole city of Chios, but soon the town expanded outside the precinct of its walls to its present size. Their emblem, three towers and an eagle, still exists in towers and battlements, which are in quite good condition.
The castle is entered over the recently filled wide moat that surrounds the castle through the southern Central Gate (Porta Maggiore), which the Venetians reconstructed in 1694. Near the gate and through an arcade, in an enclosed area, one can find the Ioustiniani Palace, an interesting building of the 15th century that has recently been renovated and it is now a worthy permanent exhibition. In the same area, one can also see the prison, as well as the tomb of Kara Alis. Also, along the central road of the Castle, stands the church of Saint George and - to the north - the Turkish Baths. The Krya Vrysi (Cold Fountain), a semi-subterranean water cistern built during the Genoese occupation, is one of the two most important structures inside the castle. The second one is a massive tower known as "Kulas", the Turkish Tower.
The first architectural phase of the monument dates from the end of the 10th century (Byzantine period) but almost nothing has survived of the original fortification. The series of additions, reinforcements and repairs by the Genoese, the Venetians and the Turks in the period from the early 14th century until the Greek War of Independence made the present form of the castle. However, the castle suffered severe disasters such as a bombardment in 1828 and an earthquake in 1881, and at the beginning of the 20th century it was seriously damaged when the whole southern part was demolished for the construction of the dock of the modern town. In recent years, important evidence for the morphology and the history of the fortress has been brought to light by excavation research carried out in private plot during the construction of modern houses.
In the course of the recent restoration work, the facade of the building called "Dark Dungeon" has been cleared, its masonry has been repaired, the main entrance of the castle has been consolidated and its roof has been reinforced. Also the vault of the entrance of the castle has been consolidated, the wall masonry has been repaired and the recent plastering has been removed. The joints of the stones of the SE bastion were also repaired and the passageway on the walls was cleared over the main gate, revealing a pavement. The castle today is a habitation area.
One of the four towers that the castle used to have on the four corners of its rectangular part. It is circular and the two floors that it consists communicate through a spiral staircase. Only three of the towers are still exist nowadays. (Unfortunately, the one, which is located at the corner where the parking area is, these days has been destroyed). One of the three existing towers is a very unique one since it has circular rooms. A tunnel parallel to the outer road connected the towers with each other.
The visitor can still notice the loopholes of the tower. Although from inside they look like tunnels however they look as narrow openings from outside. By taking the ring road from the tower, one reaches the entrance of the village-castle.
The main road from the Proskynima leads to the Northwest side of the castle, which is called "tower of Militas". "Militas" comes from the Italian word militare, which means army. The visitor can see more clearly the tower from the square outside the castle. A military force reinforced the castle since it is located facing the sea from where all raids were expected; this is the reason that it was named after this word.
It is worth to mention the following in order to show the significance of the tower in terms of the defence of the castle, as well as the effective of the entire system of defence of the village:
The castle had a quadrilateral shape with a triangular peak on the Northwest side that ended to the "Tower of Militas". This was the defence in the front line of. Inside, according to what it is showed in the village plan, two roads that started from the square and converged just before the tower of Militas formed a castle inside the main castle. That was the defence in the second line. The third line of defence is made by the main tower where the church of Big Taxiarchis is located. The central tower received all visual messages sent from the highest mountain of the area, Merovigli (=the watch tower of the daytime), and motivated the whole system of defence
The tower of Militas played the most significant role in the repulse of the raiders; this was helped by its position; it also protected the most important good for the besieged, the water. The well is located in the inner part of the castle in a shed under the tower. In order to draw water out, the ruts on the mouth of the well have been made by the ropes, which have been going up and down for centuries. Some new slabs were placed over the old ones but they were also worn when they showed signs of wear. There was also an underground tunnel that used to link the well with the central tower of the castle, so if the enemies have reached the village but not the tower, the besieged people would have water supplies.
The gate, which exists in the tower of Militas, is built more recently. Perhaps, there was an emergency gate of the castle at that point. The road from the tower of Militas on the back way, leads to the triangle, which has the two inner roads of the The visitor can see remains of another tower at the house, which is in the corner of the two roads.
The name of the Gateway of the castle derives from the Italian word "capitano" as it comes from the natives as "door of the captain", that means the door of the governor. The iron door remains in a very good condition. The monoliths of which it consists are remarkable as well. The door was opened in the morning at sunrise and closed in sunset during the Genoan occupation. That happened everyday and not only when there was a danger of a raid. It is because the village was the place of the natives' dwelling but at the same time it used to exist as a camp for the conquerors. This gate was the only one on the castle so the conquerors could easily check the entry of the products, especially of mastic.
The house has been named after him because it must have been the governor's-captain's residence over and next to the door gate. The small window through which the guards used to observe the residents' entry-exit is noticed at the inside part of the gate.
Two of the most ancient churches of the village are located on the way into the castle. The first one is that of Aghios Georgios and the second one is that of Aghia Paraskevi, the latter of which is more significant.