Amasya Castle sits atop the ridge of Mount Harşena, dominating both the gorge and the valley below. The walls you walk today are largely Byzantine and Ottoman in their final form, but they follow the outline of a Pontic fortification that was already ancient when Alexander the Great passed through the region in the fourth century BC. Getting up here requires a steep climb — there are steps cut into the rock, and the path is well-marked — but the views across the Yeşilırmak gorge and into the valley make it entirely worthwhile.
Inside the castle walls are cisterns, tunnels cut deep into the mountain, and the ruins of various towers and gatehouses. The walls themselves have been consolidated rather than over-restored, so the texture of accumulated centuries — Byzantine stonework patched with Seljuk and Ottoman additions — is still legible. Plan an hour at minimum, more if you want to explore the upper bastions and the tunnel network. Bring water; there is nothing to buy up here.