The Upper Fortress
Of the Upper Fortress located on the peak of the hill on which the city rests, the round planned tower and some of the walls have survived to this day. This fortress was built as a defensive structure in the 13th century CE on a strategic hill of the city and region. It is known that the king of Nicaea (Iznik) Ioannes Ducas Vatatzes and the sultan of the Seljuks Giyaseddin Keyhüsrev II signed a treaty in this fortress.
Tower of the Upper Fortress