Most people take the new road, for the shorter drive, but along the old road back from Mt. Nemrut to Kâhta, you'll pass more remarkable relics of Commagene in the small village of Eski Kâhta. Don't confuse Eski Kâhta, this historical site on the mountain slope, with Kâhta, where people stay. They're about 15 km (9 miles) apart. Cross the Kâhta River on the Seljuk Bridge to see Arsameia, now called Eski Kale (Old Castle), a former capital of the Commagene kingdom.
Here, carved into the rock, is a stunning relief of Antiochus I's father, Mithridates, being greeted by Heracles. Higher up on the rock face are inscriptions proclaiming the glory of the Commagene dynasty and a tunnel heading into the mountain; on the top of this peak stand the foundations of an ancient acropolis with colored floor mosaics.
A short distance down the road from the old castle is Yeni Kale (New Castle), built by the Mameluks over a smaller Commagene fortress. Recross the Kâhta via the Cendere Köprü, a single-span bridge with two tall columns on one end and one on the other, built by the Roman emperor Septimus Severus in the early 3rd century AD. Ten kilometers (6 miles) before Kâhta is Karakuş (which means "black bird" in Turkish), named for the black eagle that guards, from atop a large column, the tombs of the royal ladies of Commagene.