Pertek Castle stands on a rocky island in Keban Dam Lake, on the route many travellers use between Elazig and Tunceli. The old fortress has been reshaped by the modern reservoir: what was once a defensive height now rises from blue water, with the ferry crossing and surrounding mountains giving it a strange, memorable setting.
It is not in central Tunceli, so treat it as part of the journey in or out rather than a casual city walk. If you are arriving from Elazig, the castle view is the moment the trip starts to feel like Dersim.