Harmantepe Castle
In order to protect the eastern border of Byzantium, in the north of Adapazarı Harmantepe village, XI. or XIII. It is one of the defensive structures built in the 19th century, which has the characteristics of outposts and watchtowers facing each other along the western bank of the Sakarya river. It has been registered as a cultural property to be protected by the decision of the Cultural and Natural Heritage Preservation Board. It is one of the castles that has survived to the present day in its strongest form among the castles in the Lower Sakarya basin. The castle, which has a round plan in the shape of an ellipse, was built with local stones. The thickness of the city walls varies between 2 meters and heights of 8-10 meters. There are 6 bushes with an average size of 5 x 5 meters.
