Kastamoni (Byzantine Kastamon) is a province in Turkey. Today it's called Kastamonu (in Turkish), but it's also referred to as Kastambol or Kastambolu. The main city of Kastamoni is Inepoli (today Inebolu ). Kastamoni is located at the base of a mountain, at which a fortress existed in the Byzantine period. Many believe that Kastamoni was originally called 'Kastron Komneni' (Kastron - Greek for castle, Komeneni - referring to the Komnene Empire of Pontus).
Source: The Encyclopaedia of Pontian Hellenism