During the Ottoman period Margariti was an important administrative and economic center of Thesprotia. Its castle was built in 1549 by the Turks on a low hill SE of the settlement, in order to strengthen their position against the Venetians who dominated the Ionian coast. The latter captured and destroyed the castle in 1571. The Turks gained Margariti again in 1573. The castle was rebuilt to a great extent in the 2nd half of the 17th or the beginning of the 18th century and must have played an important role in the historical events of the region until the beginning of the 19th century.
The fortress has an irregular polygonal shape, with its entrance located to the west. Its walls are constructed of coarsely worked stones and strong mortar and its defense capability is reinforced by a quadrilateral bastion in the north and a semicircular one in the south. It consists of two inner courtyards connected through an arched gate. The lower one is triangular and surrounded by the northern and western parts of the fortification. The upper courtyard is the main defensive core of the castle. It is surrounded by vaulted constructions used as storage rooms as well as water tanks. The walls and the floors of the latter ones was covered by hydraulic mortar and their entrances were small openings at a height of 1,50 m. from the ground. The higher level, above the vaulted constructions on the west and south side of the castle, was a fortified residence of the castle guard.