Mezek Fortress is a medieval stronghold constructed in the 11th and 12th centuries west of the modern village of Mezek, southeastern Bulgaria. It has been identified as the medieval Neoutzikon, mentioned in Byzantine chronicles. The structure is perched on an elongated terrace at the foothills of the most northeastern ridge of the Rhodope Mountains known as Gorata or St Marina. It functioned as a border guard fortress defending the lands between the rivers Maritsa and Arda. The fortress was controlled by the Byzantine and the Bulgarian Empires until it was conquered by the Ottoman Turks in the second half of the 14th century.