Looming above the northern bank of the river is a sheer rock face with the conspicuous rock-cut Tombs of the Pontic Kings. The tombs, chiselled deep into the limestone as early as the 4th century BC, were used for cult worship of the deified rulers. Up close, they aren't that impressive, and some are covered in graffiti and have a distinct whiff of urine. They're much more striking when viewed, as a whole, from the southern bank of the river.
There are more than 20 (empty) tombs in the valley but there are four that you can walk up to. Climb the wooden steps from the souvenir stalls to the ticket office. Watch where you're stepping; the steps are poorly maintained and some are broken in places. Just past the office the path divides. Turn right to head to the Tombs of Mythridates I, Ariobarzan & Mythridates II, the first three kings of the kingdom of Pontus. There are impressive panoramas of the Amasya valley from up here. Turning left from the ticket office brings you first to the remnants of the Baths of the Maidens Palace, built in the 14th century. Afterwards, continue on through a rock-hewn tunnel to arrive at the Tombs of Mythridates III & Pharnaces I, the fourth and fifth kings.
At night the entire caboodle is lit up in a memorably garish fashion.