Open to attack from the sea, Sinop was first fortified by the Hittites around 2000 BC. The existing walls are additions made by the Romans, Byzantines, Seljuks and Ottomans of those erected in 72 BC by Pontic King Mithridates VI. At one time the walls, some 3m thick, were more than 2km long, with 25m-high towers and seven gates, including still extant Kumkapı (Sand Gate) and Lonca Kapı (Guild Gate) to the northwest.
Between the two gates and next to the village otogar is a statue of Diogenes the Cynic , the Greek philosopher born in Sinop in about 413 BC.
