Guide
Seyifler Castle is a Byzantine fortress near the village of Seyifler in the Ferizli district of Sakarya, a small castle of eighty by eighty metres. Its date of construction is not known for certain; it is thought to have been built in the twelfth or thirteenth century.
It stands on the peninsula where the Sakarya river meets the Çark stream, on the strategic ground called Mesonesion, the middle island, in antiquity. What survives is two towers by the stream with a stretch of wall running between them; behind them, in ground now used as fields, the remains of thick walls survive largely ruined, with the lines of the foundations still readable. The walls are faced in stone with rubble filling between.
Seyifler, also called Kara Çepiş, and the castle of Harmantepe, also called Ab-ı Sufi, were held to matter for the conquest of the country north of the Sakarya. Akça Koca himself put the proposal to take them to Orhan Bey. Seyifler became Orhan Gazi's base and was used for campaigns towards the Black Sea coast, to the west and to the south-east. With the taking of Seyifler, Kapucak (Kaynarca) Hisar, Göl-begi (Mağara) and Karasu (Kerasse), the Ottoman principality became, by a date as early as August 1304 and soon after its founding, a considerable political and military power holding the coasts from Kocaali and Karasu as far as the boundaries of Kocaeli.
